added todo for ABC

nova/auth/ldapdriver.py

@@ -57,6 +57,10 @@ flags.DEFINE_string('ldap_developer',
     'cn=developers,ou=Groups,dc=example,dc=com', 'cn for Developers')
 
 
+# TODO(vish): make an abstract base class with the same public methods
+#             to define a set interface for AuthDrivers. I'm delaying
+#             creating this now because I'm expecting an auth refactor
+#             in which we may want to change the interface a bit more.
 class AuthDriver(object):
     """Ldap Auth driver