Summary: This allows users to set their HTTP access passwords via Diffusion interface.
Test Plan: Clicked the "Set HTTP Access Password" link, set a password and saw it appear in the DB.
Reviewers: #blessed_reviewers, hach-que, btrahan
Reviewed By: hach-que
CC: Korvin, epriestley, aran, jamesr
Maniphest Tasks: T2230
Differential Revision: https://secure.phabricator.com/D7462
