In Owners Packages, make the API representation of the "Auditing" field more consistent

Summary:
Ref T13244. See PHI1047. A while ago, the "Review" field changed from "yes/no" to 20 flavors of "Non-Owner Blocking Under A Full Moon". The sky didn't fall, so we'll probably do this to "Audit" eventually too.

The "owners.search" API method anticipates this and returns "none" or "audit" to describe package audit statuses, so it can begin returning "audit-non-owner-reviewers" or whatever in the future.

However, the "owners.edit" API method doesn't work the same way, and takes strings, and the strings have to be numbers. This is goofy and confusing and generally bad.

Make "owners.edit" take the same strings that "owners.search" emits. For now, continue accepting the old values of "0" and "1".

Test Plan:

• Edited audit status of packages via API using "none", "audit", "0", "1" (worked), and invalid values like "quack" (helpful error).
• Edited audit status of packages via web UI.
• Used owners.search to retrieve package information.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13244

Differential Revision: https://secure.phabricator.com/D20091