Self-install fix

This release fixes the self-install issue which was preventing TravisCI from running tests.

Refs: #98

Support for node version 8.0.0 and above

With the transition from node.js v7 to v8 the behavior of process.cwd() and a few other functions (like path.relative) changed. Commitplease used to rely on those functions in order to determine the location of the git project directory.

To support node.js v8 and above, all those functions were substituted with a different approach: npm injects path to node_modules when running scripts, so that injection is used.

At the same time, support for node 0.12 was dropped, which allowed to drop object-assign and ends-with shims and rely on the more modern javascript.

Refs: #98

Global install support

This release enables commitplease to be installed globally and be manually executed from console (previously it was always executed automatically as a git hook). Global executable respects repo-local settings and can check more than just the latest commit:

Use case	command
Check all commits on branch master	commitplease master
Check all commits on branch feature that are not on master	commitplease master..feature
Check all commits on current branch that are not on master	commitplease master..HEAD
Check the latest 1 commit	commitplease -1
Check all commits between 84991d and 2021ce	commitplease 84991d..2021ce
Check all commits starting with 84991d	commitplease 84991d..

Here you can read more about git commit ranges. To start using global executable, install it with

npm install -g commitplease

Angular support

This release introduces the style option, defaulting to jquery (as before), adding the angular alternative. This preset matches the Angular commit message style guide. To start using this, set the style property in your package.json:

{
  "name": "my-package",
  "devDependencies": {
    "commitplease": "2.5.0"
  },
  "commitplease": {
    "style": "angular"
  }
}