For apps in PUBLIC_WAITING state, current_version should return PUBLIC version as well (bug 895432)

https://bugzilla.mozilla.org/show_bug.cgi?id=895432

The app is still in `STATUS_PUBLIC_WAITING` when we reach `get_version()`, but the File associated to the version has already been set to `STATUS_PUBLIC`. I dismissed this as an edge case when touching `get_version()` the other day but it turns out, it's easy to reproduce now that we can publish version independently.

Also, if the current_version of an app was published, publish that app as well if it was in WAITING state.