Implementing models for instance groups, updating task manager

* New InstanceGroup model and associative relationship with Instances
* Associative instances between Organizations, Inventory, and Job
  Templates and InstanceGroups
* Migrations for adding fields and tables for Instance Groups
* Adding activity stream reference for instance groups
* Task Manager Refactoring:
** Simplifying task manager relationships and move away from the
   interstitial hash tables
** Simplify dependency determination logic
** Reduce task manager runtime complexity by removing the partial
   references and moving the logic into the task manager directly or
   relying on Job model logic for determinism

awx/main/models/projects.py

@@ -509,3 +509,12 @@ class ProjectUpdate(UnifiedJob, ProjectOptions, JobNotificationMixin):
 
     def get_notification_friendly_name(self):
         return "Project Update"
+
+    @property
+    def preferred_instance_groups(self):
+        if self.project is not None and self.project.organization is not None:
+            organization_groups = [x for x in self.project.organization.instance_groups.all()]
+        else:
+            organization_groups = []
+        template_groups = [x for x in super(ProjectUpdate, self).preferred_instance_groups]
+        return template_groups + organization_groups