Add trial initializer servlet

This is a one-time servlet called to initiate trials on all existing storage buckets.  It uses the store trial auth api to call an initial trial for each bucket.  If a trial initiation attempt returns something other than success or "company not found" then that batch will be re-tried.  It's expected that most buckets will have companies associated with them, but some may not (eg: test buckets).
@alex-deaconu Please review.  
@EnlightenedCode FYI