Add new badges to README.md

Next to title:
* Added "version" badge.
* Added "gittip" badge.

Underneath title:
* Added "node" badge.
* Added "grunt" badge.
* Updated "build" badge (travis-ci) to use SVG instead of PNG.
* Added "dependency" badges (david-dm).
* Added "code-climate" badge.
Merge pull request #177 from markcarver/badges

Add new badges to README.md
Fixed issue.getNewCommentNumber

Fixes #181.
Merge pull request #182 from markcarver/issue/181

Updated issue.getNewCommentNumber for restyled d.o comments.
Added (diff) syntax highlighting for code review comments.