Creating (or updating) a Phriction Document creates empty parent documents

Summary:
Fixes T2208

Parent documents get created as stubs - while the action is "parent" - don't ask

Test Plan: Created some documents with somewhat ancestry - verified their parents had pages and stub messages display ({F34456}).

Reviewers: epriestley, btrahan

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T2208

Differential Revision: https://secure.phabricator.com/D5201