Render deleted files in Phragment as disabled
Summary: This updates Phragment so that fragments that are currently considered deleted have a disabled status and have an additional attribute 'Deleted'. It also places this effect on versions (in the history controller) that actually involve deleting the file.
Test Plan: Viewed deleted fragments and versions.
Reviewers: epriestley, Blessed Reviewers
Reviewed By: epriestley
CC: Korvin, epriestley, aran
Maniphest Tasks: T4205
Differential Revision: https://secure.phabricator.com/D7737