Phriction - move delete business logic from controlller to editor

Summary: Ref T4029. More cleanup and code consolidation for the long terms benefits.

Test Plan: found a document and opened up two browser tabs. Loaded delete dialog on both. Completed delete in one tab and noted document was properly deleted. Tried to complete delete in tab 2 and got an error message.

Reviewers: chad, epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T4029

Differential Revision: https://secure.phabricator.com/D10809