Escalate reviews for apps with prerelease permissions (bug 1036921)

https://bugzilla.mozilla.org/show_bug.cgi?id=1036921

Depends on mozilla/app-validator#33.

This will escalate the review of new and updated packaged apps if they use any of the prerelease permissions that are switching to privileged from certified.
are you creating a fake escalation review here?  
In https://github.com/mstriemer/zamboni/blob/escalate-prerelease-permissions-1036921/mkt/developers/utils.py#L128 I just created the note, etc.  Is this way better?