Use GGRC extension modules for notifications and minor cleanup prior to fixing Task Undo and remaining notification issues
Merge remote-tracking branch 'origin/develop' into feature/email_notification_task_undo
Fixes for Task/Undo handling of email notification including parent taskgroup.
Added cron entries for emails related Task/TaskGroup state as well Task Reassign to run every 10 minutes
Fix start workflow and noisy emails
Modify cron to run every 10 min
Handling all deferred notification created 10 min prior to the Cron job
Use UTC time for checking deferred emails (10 min instead of 60 min) instead as SQLAlchemy stores datetime field as UTC by defaut.
Fix for generating email notification for End cycle (leverages is_current attribute)
Also has minor cleanup, merged the prior pull request with latest branch
Merge remote-tracking branch 'origin/feature/email_notification_task_undo' into feature/email_notification_end_cycle

Conflicts:
	src/ggrc_workflows/__init__.py
Merge pull request #1583 from reciprocity/feature/email_notification_end_cycle

Generate email notification for End cycle