R1:0c4eb79d3a54

Allow Phame posts to be loaded by handle

Summary: Primarily, this makes flagging work on them.

Test Plan: Flagged / Unflagged a post.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T1373

Differential Revision: https://secure.phabricator.com/D3702