fix security_groups's rules comparision

Neutron recently added 'revision' key to security group rule's output
but incoming rule doesn't contain (and doesn't care about) such key.
patchset adds this key to exclude's list.

Change-Id: I89350e40834dae118acc4cfafe3c6e09e36737c2

ec2api/api/security_group.py

@@ -336,7 +336,7 @@ def _are_identical_rules(rule1, rule2):
             if (value is not None and value != -1 and
                     value != '0.0.0.0/0' and
                     key not in ['id', 'tenant_id', 'security_group_id',
-                                'description']):
+                                'description', 'revision']):
                 dict[key] = str(value)
         return dict