R1:9c5a6601d6b0

Remove some Mercurial and Google caveats

Summary: These seem to work relatively reasonably and don't have any known
deal-breaking failures.

Test Plan: shrug~

Reviewers: btrahan, jungejason

Reviewed By: btrahan

CC: aran, btrahan

Differential Revision: https://secure.phabricator.com/D1324