Dropped stored role name/description and other superflous fields

For name and description, we'll derive these from the role_field and
content type, which is much better for lots of reasons (eg changing text
the future). Also ditched the rest of the fields comming from the
standard common base model, we didn't use them and they cost several
indexes on the table.

awx/main/tests/functional/test_rbac_project.py

@@ -148,7 +148,7 @@ def test_project_user_project(user_project, project, user):
 def test_project_accessible_by_sa(user, project):
     u = user('systemadmin', is_superuser=True)
     # This gets setup by a signal, but we want to test the migration which will set this up too, so remove it
-    Role.singleton('System Administrator').members.remove(u)
+    Role.singleton('system_administrator').members.remove(u)
 
     assert u not in project.read_role
     rbac.migrate_organization(apps, None)