Added abbreviated month + test.
Changed to short_month and re-ran tests.
Remove pygments as a dependency

Pygments is bundled in pygments.rb it's no longer required
to be installed by the user.
Merge pull request #921 from tombell/patch-1

Remove pygments as a dependency
Merge pull request #890 from zachgersh/abbreviated_month

Added abbreviated month + test.
Update history to reflect merge of #890
Upgrade pygments.rb to 0.4.2. Fixes #927