Filter out deleted users and organizations from the superuser list

Superusers were getting confused because the users/orgs were being disabled and renamed, but still appeared in the list until they were GCed by the background worker. Now we just hide them.

Fixes https://jira.coreos.com/browse/QUAY-936

data/model/organization.py

@@ -1,6 +1,6 @@
 
 from data.database import (User, FederatedLogin, TeamMember, Team, TeamRole, RepositoryPermission,
-                           Repository, Namespace)
+                           Repository, Namespace, DeletedNamespace)
 from data.model import (user, team, DataModelException, InvalidOrganizationException,
                         InvalidUsernameException, db_transaction, _basequery)
 
@@ -145,8 +145,13 @@ def get_all_repo_users_transitive_via_teams(namespace_name, repository_name):
           .where(Namespace.username == namespace_name, Repository.name == repository_name))
 
 
-def get_organizations():
-  return User.select().where(User.organization == True, User.robot == False)
+def get_organizations(deleted=False):
+  query = User.select().where(User.organization == True, User.robot == False)
+
+  if not deleted:
+    query = query.where(User.id.not_in(DeletedNamespace.select(DeletedNamespace.namespace)))
+
+  return query
 
 
 def get_active_org_count():