Fix issue when creating a new mock in Pholio

Summary: Fix T2573. The way Lisk works, we try to save "protected" fields to the database. For non-database data, use "private".

Test Plan: Created a new mock.

Reviewers: chad, ljalonen

Reviewed By: chad

CC: aran

Maniphest Tasks: T2573

Differential Revision: https://secure.phabricator.com/D5053