Add support for finding programs by air status
Add conditional query to Program model

* Updates Program API controller to use it (v3 only)
* Cleans up some tests
(pmp) Protect against empty timestamp; don't memoize root document
Merge pull request #192 from SCPR/features/add-find-by-air-status-to-v3-api

Add support for finding programs by air status
Bump API version [ci skip]
Remove warning in test
Protect against missing alt link
Merge remote-tracking branch 'origin/master' into mounted-routes