Make exception reporting from arc be in red
Many other status updates (such as "Builds passed!") show up
in bright background colors, making them more salient than a final
Make exception reporting be just as colorful, so it stands out.
Added an explicit throw new Exception("!!!") and saw it
Reviewers: Blessed Reviewers, epriestley
Reviewed By: Blessed Reviewers, epriestley
Differential Revision: https://secure.phabricator.com/D17748