CYB-122 Sync activity updating
* fixed issues with builders (no such field as 'uid' and was missing fields as well)
* student scores are recomputed and cached on call to Activity.update_scores!
  * This is called by the EngagementIndexScoringProcessor, which in turn is called by the cron updater and the thor (hand) updater
Merge pull request #60 from coyote/sync_activity_updating

Sync activity updating