Merge branch 'develop'

* develop: (47 commits)
  Migrated Travis CI from .org domain to .com
  Add shell script to push test coverage results to CodeClimate
  Add linters and commit hooks to validate code prior to commits
  Fix bug in Travis CI config
  Bump version to `2.1.0`
  Update Travis CI config to build with latest dependencies and no development gems
  Move gem development dependencies into the `Gemfile`
  Add `:mode` config option; values `:loose`, `:moderate`, `:strict`; default to `:loose`
  Update config for Travis CI
  [readme] Update TravisCI badge URL
  [readme] Add alternate gem `email_verifier`
  [readme] Add alternate gem `email_address`
  Update `CHANGELOG`; bump version to `1.9.0.pre`
  Add `require_fqdn` option, require FQDN by default
  Add support for IPv4 and IPv6 address hosts
  Add Rubocop, `.editorconfig`; code cleanup/linting
  RSpec: Configure zero-monkey-patching mode
  whitespace
  Regex tweak
  [readme] Update `README` to show installating from `karlwilbur` GitHub repo.
  ...

.editorconfig

@@ -0,0 +1,18 @@
+root = true
+
+[*]
+indent_style = space
+indent_size = 2
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+# Ignore paths
+[*.{enc,lock}]
+charset = unset
+end_of_line = unset
+insert_final_newline = unset
+trim_trailing_whitespace = unset
+indent_style = unset
+indent_size = unset

.gitignore

@@ -1,22 +1,36 @@
-## MAC OS
+
+# Build artifacts
+*.gem
+*.rbc
+
+# Bundler artifacts
+.bundle
+Gemfile.lock
+
+# Development artifacts
+node_modules
+yarn-error.log
+yarn-debug.log*
+.yarn-integrity
+.byebug_history
+rdoc
+pkg
+.rspec
+.config
+.env
+
+# OS artifacts
 .DS_Store
 
-## TEXTMATE
+# IDE/Editor artifacts
+*.code-workspace
 *.tmproj
 tmtags
-
-## EMACS
 *~
 \#*
 .\#*
-
-## VIM
 *.swp
 
-## PROJECT::GENERAL
-Gemfile.lock
+# SimpleCov artifacts
 coverage
-rdoc
-pkg
 
-## PROJECT::SPECIFIC

.markdownlint.style.rb

@@ -0,0 +1,224 @@
+# frozen_string_literal: true
+
+# Markdownlint style file
+# File syntax: Ruby (Markdownlint Style DSL)
+#
+
+# Refs:
+#    Ruby version
+#        Config: https://github.com/markdownlint/markdownlint/blob/master/docs/configuration.md
+#        Styles: https://github.com/markdownlint/markdownlint/blob/master/docs/creating_styles.md
+#        Rules: https://github.com/markdownlint/markdownlint/blob/master/docs/RULES.md
+#    JS version (modeled after the Ruby version)
+#        https://github.com/DavidAnson/markdownlint/blob/master/doc/Rules.md
+#
+#
+# Many of the defaults used by Markdownlint are chosen because of how renderers
+# interpret Markdown. The defaults are chosen for the greatest compatability and
+# confidence in proper rendering of the Markdown; for text-only viewing, it is
+# less relevant.
+
+# Enabled all rules
+#
+# This is makes many of the rules defined below, where they are just being
+# enabled and running with the defaults, unnecessary. They've been left in for
+# explanatory purposes.
+all
+
+# MD001 - Header levels should only increment by one level at a time
+rule 'MD001'
+
+# MD002 - First header should be a top level header
+rule 'MD002'
+
+# MD003 - Header style
+# Default: always use the same header style of any of the allowed header styles
+#
+# Headers should use the `#` ('atx') style headers
+rule 'MD003', :style => :atx
+
+# MD004 - Unordered list style
+# Default: always use the same character (any one of `*`,`+`,`-`)
+#
+# Do not force a single unordered list character, we should be using them to
+# visually indicate nested lists. Since this rule cannot support validating
+# our usage, we are disabling it.
+exclude_rule 'MD004'
+
+# MD005 - Inconsistent indentation for list items at the same level
+# Default: don't allow inconsistent indentation for list items
+rule 'MD005'
+
+# MD006 - Start bulleted lists at the beginning of the line
+rule 'MD006'
+
+# MD007 - Unordered list indentation
+# Default: 2 spaces
+#
+# Use 4 spaces because using 2 doesn't always render a sublist.
+rule 'MD007', :indent => 4
+
+# No rule MD008
+
+# MD009 - Trailing spaces
+# Default: trailing spaces not allowed
+rule 'MD009'
+
+# MD010 - Hard tabs
+# Default: hard tabs not allowed
+rule 'MD010'
+
+# MD011 - Reversed link syntax
+# Default: alert when link syntax seems to be reversed
+#          (the `[]` and `()` are reversed)
+rule 'MD011'
+
+# MD012 - Multiple consecutive blank lines
+# Default: No multiple consecutive blank lines
+rule 'MD012'
+
+# MD013 - Line length
+# Default: Max 80 characters per line
+#
+# Set line length limit to 120 characters (default: 80 characters)
+rule 'MD013', :line_length => 120, :code_blocks => false
+
+# MD014 - Dollar signs used before commands without showing output
+# Default: No dollars signs before shell commands w/o showing shell output
+rule 'MD014'
+
+# No rule MD015 to MD017
+
+# MD018 - No space after hash on atx style header
+# Default: Must have space after header style
+rule 'MD018'
+
+# MD019 - Multiple spaces after hash on atx style header
+# Default: No multiple spaces after hash in header
+rule 'MD019'
+
+# MD020 - No space inside hashes on closed atx style header
+# Default: Must have space before closing hash in closed atx style headers
+#
+# We don't use closed ATX style headers
+rule 'MD020'
+
+# MD021 - Multiple spaces inside hashes on closed atx style header
+# Default: No multiple spaces before closing hash in closed atx style headers
+#
+# We don't use closed ATX style headers
+rule 'MD021'
+
+# MD022 - Headers should be surrounded by blank lines
+# Default: Must have a blank line above and below headers
+rule 'MD022' # headers should be surrounded by blank lines
+
+# MD023 - Headers must start at the beginning of the line
+rule 'MD023'
+
+# MD024 - Multiple headers with the same content
+# Default: No multiple headers with same content, no duplicate header text
+rule 'MD024', :allow_different_nesting => true
+
+# MD025 - Multiple top level headers in the same document
+# Default: The is onlt one level 1 header; it's the title of the document
+rule 'MD025'
+
+# MD026 - Trailing punctuation in header
+# Default: No trailling punctuation in headers
+rule 'MD026'
+
+# MD027 - Multiple spaces after blockquote symbol
+# Default: Only a single spaces after blockquote symbol
+rule 'MD027'
+
+# MD028 - Blank line inside blockquote
+# Default: Blockquote right next to each other must have text between them
+rule 'MD028'
+
+# MD029 - Ordered list item prefix
+# Default:
+#
+# ordered list item prefix, should be ordered
+rule 'MD029', :style => :ordered
+
+# MD030 - Spaces after list markers
+# Default: Only one space character after a list marker
+rule 'MD030'
+
+# MD031 - Fenced code blocks should be surrounded by blank lines
+# Default: Fenced code blocks ("```") must have a blank line above and below
+rule 'MD031'
+
+# MD032 - Lists should be surrounded by blank lines
+# Default: Lists must have a blank line above and below the list (not each item)
+rule 'MD032'
+
+# MD033 - Inline HTML
+# Default: No raw HTML
+rule 'MD033'
+
+# MD034 - Bare URL used
+# Default: No bare URLs
+rule 'MD034'
+
+# MD035 - Horizontal rule style
+# Default: Be consistent, use only one of `---`, `- - -`, `***`, or `* * *`
+#
+# We want to enforce `---`
+rule 'MD035', :style => '---'
+
+# MD036 - Emphasis used instead of a header
+# Default: Do not use emphasis (bold, italic, etc) as header, use actual headers
+rule 'MD036'
+
+# MD037 - Spaces inside emphasis markers
+# Default: No leading/trailing spaces inside emphasis markers
+rule 'MD037'
+
+# MD038 - Spaces inside code span elements
+# Default: No leading/trailing spaces inside code markers ("`")
+rule 'MD038'
+
+# MD039 - Spaces inside link text
+# Default: No leading/trailing spaces inside link text ("[]")
+rule 'MD039'
+
+# MD040 - Fenced code blocks should have a language specified
+# Default: Fenced code blocks ("```") must have a language specified
+rule 'MD040'
+
+# MD041 - First line in file should be a top level header
+# Default: First line in file must be a top level header
+rule 'MD041'
+
+# Rule MD042 to MD045, and MD047 are only supported by the JavScript version
+
+# # MD042 - No empty links
+# # Default: Links URLs cannot be empty; empty fragments (`#`) are still empty
+# rule 'MD042'
+
+# # MD043 - Required heading structure
+# # Default: disabled
+# #
+# # This requires headings from a predetermined list (`headings` array).
+# rule 'MD043'
+
+# # MD044 - Proper names should have the correct capitalization
+# # Default: names: nil, code_blocks: true
+# #
+# # This preforms a case-insensitive search for srtings from the `names` array.
+# # then checks capatilization of those strings against the element from `names`
+# rule 'MD044'
+
+# # MD045 - Images should have alternate text (alt text)
+# # Default: Alt text is required for all images
+# rule 'MD045'
+
+# MD046 - Code block style
+# Default: Always used fenced code blocks ("```")
+rule 'MD046'
+
+# # MD047 - Files should end with a single newline character
+# # Default: Requires newline at end of file
+# rule 'MD047'

.mdlrc

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+# Markdownlint style file
+# File syntax: Ruby
+#
+# This file is used by the version of Markdownlint in the CodeClimate image:
+#    `codeclimate/codeclimate-markdownlint`
+#
+# It can also be used by the `markdownlint` gem when run directly, outside of
+# CodeClimate.
+#
+
+style './.markdownlint.style.rb'