R1:3c8d88deb454

Don't warn about conflicts when reverting Phriction documents

Summary:
Fixes T5144. This was incorrectly checking the //content// version, not the //head// version, so reverts would raise the "conflict" warning.

Also fix a couple of FontAwesome icons.

Test Plan:
- Edited a document.
- Reverted a document.
- Opened two edit tabs. Edited one, tried to edit #2, got a warning.
- Opened two revert tabs. Reverted in one, tried to revert in #2, got a warning.

Reviewers: btrahan, chad

Reviewed By…