Populate ActionItem model from bugzilla, polls and events.

* Sync [waiting <item>] action items from bugzilla.
* Sync pending_mentor_validation action items from bugzilla.
* Sync budget_needinfo action items from bugzilla.
* Sync council reviewer assignment action items from bugzilla.
* Change ActionItem model fields.
* Create action items only for bugs assigned to Reps.
* Add new action item on new poll.
* Resolve action item on new vote.
* Add new action item to submit post event metrics.
* Resolve action item when post event metrics are submitted.
By doing this, you are marking as resolved and completed an action item that the user might not took action. Eg if a bug is marked as RESOLVED but the user did not remove the needinfo flag, this will mark the action item as completed which is not correct.