Rearchitect project update strategy

* Instead of using a fanout for project updates initial project
  updates will sync the latest commit hash
* Prior to a node running a job it will ensure that the latest project
  is synced

awx/main/models/projects.py

@@ -7,6 +7,9 @@ import os
 import re
 import urlparse
 
+# Celery
+from celery import group, chord
+
 # Django
 from django.conf import settings
 from django.db import models
@@ -227,6 +230,15 @@ class Project(UnifiedJobTemplate, ProjectOptions, ResourceMixin):
         blank=True,
     )
 
+    scm_revision = models.CharField(
+        max_length=1024,
+        blank=True,
+        default='',
+        editable=False,
+        verbose_name=_('SCM Revision'),
+        help_text=_('The last revision fetched by a project update'),
+    )
+
     admin_role = ImplicitRoleField(parent_role=[
         'organization.admin_role',
         'singleton:' + ROLE_SINGLETON_SYSTEM_ADMINISTRATOR,
@@ -393,6 +405,12 @@ class ProjectUpdate(UnifiedJob, ProjectOptions, JobNotificationMixin):
         editable=False,
     )
 
+    job_type = models.CharField(
+        max_length=64,
+        choices=PROJECT_UPDATE_JOB_TYPE_CHOICES,
+        default='check',
+    )
+
     @classmethod
     def _get_parent_field_name(cls):
         return 'project'