Update: group commits by types in release log (fixes #46)

[sapphi-red]

This PR implements #46.

Based on eslint/eslint:/templates/blogpost.md.ejs.

[eslint-deprecated]

Hi @sapphi-red!, thanks for the Pull Request

The first commit message isn't properly formatted. We ask that you update the message to match this format, as we use it to generate changelogs and automate releases.

• The issue reference must be formatted as follows:

  If the pull request addresses an issue, then the issue number should be mentioned at the end. If the commit doesn't completely fix the issue, then use (refs #1234) instead of (fixes #1234).

  Here are some good commit message summary examples:

  Build: Update Travis to only test Node 0.10 (refs #734)
  Fix: Semi rule incorrectly flagging extra semicolon (fixes #840)
  Upgrade: Esprima to 1.2, switch to using comment attachment (fixes #730)
  

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[nzakas]

Thanks for doing this! We need the team’s input before merging but I’m in favor. 👍

[btmills]

This is an excellent idea, thanks for doing it @sapphi-red!