In Applications, always redirect back to the detail page after edits

Summary:
Ref T12685. When you edit an application's policies but don't make any changes, you currently get stuck on the same page. This isn't how other edit screens work, and I think it's a holdover from eras long ago.

Make it consistent with other applications.

Also, fix a missing pht().

Test Plan:

• Edited an application configuation.
• Clicked "Save" without making changes.
• After patch, was redirected back to detail page like in other applications.

Reviewers: chad, amckinley

Reviewed By: chad

Maniphest Tasks: T12685

Differential Revision: https://secure.phabricator.com/D17877