Change codebase to query or create correct User model

The code base had many references to User.username and other
specific to LocalUser attributes as that was the way it use to exist.
This updates those to query on the generic User model but filtering
by attributes on the LocalUser.

mediagoblin/plugins/ldap/views.py

@@ -18,7 +18,7 @@ import six
 
 from mediagoblin import mg_globals, messages
 from mediagoblin.auth.tools import register_user
-from mediagoblin.db.models import User
+from mediagoblin.db.models import User, LocalUser
 from mediagoblin.decorators import allow_registration, auth_enabled
 from mediagoblin.plugins.ldap import forms
 from mediagoblin.plugins.ldap.tools import LDAP
@@ -38,8 +38,9 @@ def login(request):
                                   login_form.password.data)
 
         if username:
-            user = User.query.filter_by(
-                username=username).first()
+            user = User.query.filter(
+                LocalUser.username==username
+            ).first()
 
             if user:
                 # set up login in session