Inform about disabled and away users in Differential fields
Summary:
I've tried colors, italics, strike-through and this is a compromise between me and @leebyron.
NOTE: I don't want to disturb @epriestley from playing Diablo 3.
Test Plan: {F11439, size=full}
Reviewers: btrahan
Reviewed By: btrahan
CC: aran, epriestley, leebyron
Differential Revision: https://secure.phabricator.com/D2481