Allow "Custom" policies to be selected in the policy control
Summary: Ref T603. When a user selects "Custom", we pop open the rules dialog and let them create a new rule or edit the existing rule.
Test Plan: Set some objects to have custom policies.
Reviewers: btrahan
Reviewed By: btrahan
CC: aran
Maniphest Tasks: T603
Differential Revision: https://secure.phabricator.com/D7300