remove deprecated mongo fact code and deps

* We have the requirements that users with Tower < 3.0.x must upgrade to
3.0.x before > 3.0.x. Thus, we are save to delete all mongo migration
code and deps.

awx/settings/defaults.py

@@ -210,7 +210,6 @@ INSTALLED_APPS = (
     'awx.main',
     'awx.api',
     'awx.ui',
-    'awx.fact',
     'awx.sso',
     'solo',
 )

awx/settings/development.py

@@ -54,7 +54,7 @@ PENDO_TRACKING_STATE = "off"
 try:
     import django_jenkins
     INSTALLED_APPS += (django_jenkins.__name__,)
-    PROJECT_APPS = ('awx.main.tests', 'awx.api.tests', 'awx.fact.tests',)
+    PROJECT_APPS = ('awx.main.tests', 'awx.api.tests',)
 except ImportError:
     pass