Add Git Gutter+ and Git Gutter Fringe+

These are patched and improved forks of Git Gutter and Git Gutter
Fringe. See https://github.com/nonsequitur/git-gutter-plus and
https://github.com/nonsequitur/git-gutter-fringe-plus.
Remove misplaced comment

None will ever read this comment anyway…
Cleanup whitespace and indentation
Merge pull request #84 from lunaryorn/git-gutter-plus

Add Git Gutter + and Git Gutter Fringe +
Don't specify bg for ahs faces.