Fix non-public capabilities in Application edit

Summary: Ref T603. I nuked this check by accident and neglected to test the negative case.

Test Plan: Saved a non-public policy (Herald Global) and a public policy (Maniphest View).

Reviewers: asherkin, btrahan

Reviewed By: asherkin

CC: aran

Maniphest Tasks: T603

Differential Revision: https://secure.phabricator.com/D7278