Add colors to Maniphest transactions

Summary:
Add colors to Maniphest transactions. The precedence of the css
classes is determined by their occurrences in the css file. The class
shows up latter overrides the ones above it.

Test Plan:
set a task to different statuses to verify that the colors
are set.

Reviewed By: epriestley
Reviewers: epriestley
CC: jungejason, epriestley
Differential Revision: 55