Refactoring for Rakefile to display cucumber task by "rake -T". (#1088)

* Refactoring for Rakefile to display cucumber task by "rake -T".
* Remove gem_tasks/cucumber.rake.
* Unify `ruby_x_y` profiles to ruby.
* Drop unsupported JRuby and Windows from the logic.

Rakefile

@@ -9,7 +9,12 @@ Dir['gem_tasks/**/*.rake'].each { |rake| load rake }
 require 'rubocop/rake_task'
 RuboCop::RakeTask.new
 
-task :default => [:spec, :rubocop, :cucumber]
+require 'cucumber/rake/task'
+Cucumber::Rake::Task.new do |t|
+  t.profile = 'ruby' if Cucumber::RUBY
+end
+
+default_tasks = [:spec, :rubocop, :cucumber]
 
 if ENV['TRAVIS']
   ENV['SIMPLECOV']  = 'ci'
@@ -18,8 +23,10 @@ if ENV['TRAVIS']
   require 'coveralls/rake/task'
   Coveralls::RakeTask.new
 
-  task :default => [:spec, :rubocop, :cucumber, 'coveralls:push']
+  default_tasks << 'coveralls:push'
 end
 
+task :default => default_tasks
+
 require 'rake/clean'
 CLEAN.include %w(**/*.{log,pyc,rbc,tgz} doc)

cucumber.yml

@@ -13,9 +13,7 @@ default:     <%= std_opts %> --tags 'not @jruby'
 jruby:       <%= std_opts %> --tags 'not @wire'
 jruby_win:   <%= std_opts %> --tags 'not @wire' CUCUMBER_FORWARD_SLASH_PATHS=true
 windows_mri: <%= std_opts %> --tags 'not @jruby and not @wire and not @needs-many-fonts' CUCUMBER_FORWARD_SLASH_PATHS=true
-ruby_1_9:    <%= std_opts %> --tags 'not @jruby'
-ruby_2_0:    <%= std_opts %> --tags 'not @jruby'
-ruby_2_1:    <%= std_opts %> --tags 'not @jruby'
+ruby:        <%= std_opts %> --tags 'not @jruby'
 wip:         --wip <%= wip_opts %> features <%= cucumber_pro_opts %>
 none:        --format pretty --format Cucumber::Pro --out /dev/null
 rerun:       <%= rerun_opts %> --format rerun --out rerun.txt --strict --tags 'not @wip-new-core' <%= cucumber_pro_opts %>

lib/cucumber/platform.rb

@@ -11,9 +11,7 @@ module Cucumber
     LIBDIR        = File.expand_path(File.dirname(__FILE__) + '/../../lib')
     RAILS         = defined?(Rails)
     RUBY_BINARY   = File.join(RbConfig::CONFIG['bindir'], RbConfig::CONFIG['ruby_install_name'])
-    RUBY_2_2      = RUBY_VERSION =~ /^2\.2/
-    RUBY_2_1      = RUBY_VERSION =~ /^2\.1/
-    RUBY_2_3      = RUBY_VERSION =~ /^2\.3/
+    RUBY          = defined? RUBY_VERSION
 
     class << self
       attr_accessor :use_full_backtrace