Add a console highlighter and language guesser

Summary: Pygments has a console highlighter but it doesn't handle path prefixes and doesn't ephasize comments enough. Add a fancier highlighter and a guesser.

Test Plan: {F11792}

Reviewers: btrahan, vrana, jungejason

Reviewed By: btrahan

CC: aran

Differential Revision: https://secure.phabricator.com/D2539