Summary:
- Allow Celerity to map and serve WOFF files.
- Add Source Sans Pro, Source Sans Pro Bold, and the corresponding LICENSE.
- Add a `font-source-sans-pro` resource for the font.
Test Plan:
- Changed body `font-face` to `'Source Sans Pro'`.
- Added `require_celerity_resource('font-source-sans-pro')` in StandardPageView.
Works in Firefox/Chrome/Safari, at least:
{F123296}
{F123297}
{F123298}
Reviewers: btrahan, chad
Reviewed By: chad
CC: chad, aran
Differential Revision: https://secure.phabricator.com/D8430
