Add common way to extend standard attribute models

This adds a way for standard attribute models to declare
the API resources they show up in. It then adds a utility
function to the standard_attr module to grab a map of all
API resources and their corresponding models.

This can be used by any processing code that wants to add
fields to standard attribute resources.

This also adjusts the existing extensions to leverage this
new functionality.

Partially-Implements: blueprint add-neutron-extension-resource-timestamp
Change-Id: Idc8923d0e983fcb0690f8cb5b55a5aff8690154f
diff --git a/neutron/tests/tempest/api/test_revisions.py b/neutron/tests/tempest/api/test_revisions.py
index b45990f..0ecb7b8 100644
--- a/neutron/tests/tempest/api/test_revisions.py
+++ b/neutron/tests/tempest/api/test_revisions.py
@@ -20,7 +20,7 @@
 class TestRevisions(base.BaseAdminNetworkTest, bsg.BaseSecGroupTest):
 
     @classmethod
-    @test.requires_ext(extension="revisions", service="network")
+    @test.requires_ext(extension="standard-attr-revisions", service="network")
     def skip_checks(cls):
         super(TestRevisions, cls).skip_checks()