Expose any external account as a user property

This adds a field to the user object to denote whether and what kind of
user account it is.

For normal accounts this field will be null.
For social auth accounts it will be "social"
for radius accounts it will be "radius"

This change also prevents a radius user from changing their local
password thus bypassing the password caching feature of django-radius

awx/sso/backends.py

@@ -6,6 +6,7 @@ import logging
 
 # Django
 from django.dispatch import receiver
+from django.contrib.auth.models import User
 from django.conf import settings as django_settings
 
 # django-auth-ldap
@@ -104,6 +105,18 @@ class RADIUSBackend(BaseRADIUSBackend):
             return None
         return super(RADIUSBackend, self).get_user(user_id)
 
+    def get_django_user(self, username, password=None):
+        try:
+            user = User.objects.get(username=username)
+        except User.DoesNotExist:
+            user = User(username=username)
+
+        if password is not None:
+            user.set_unusable_password()
+            user.save()
+
+        return user
+
 
 class TowerSAMLIdentityProvider(BaseSAMLIdentityProvider):
     '''