Summary:
For each commit, find the affected packages, and provide a way to
search by package.
Test Plan:
create commits that touch and don't touch two packages, and verify
that they display correctly in all the UI pages.
Reviewers: epriestley, blair, nh, tuomaspelkonen
Reviewed By: epriestley
CC: benmathews, aran, epriestley, btrahan, jungejason, mpodobnik, prithvi
Maniphest Tasks: T83
Differential Revision: 1208
