Implement V2 interfaces and remaining V1 interfaces

Also adds some tests to registry tests for V1 stuff.
Note: All *registry* tests currently pass, but as verbs are not yet converted, the verb tests in registry_tests.py currently fail.

data/interfaces/common.py

@@ -0,0 +1,12 @@
+from image import Repository
+from data import model
+
+def repository_for_repo(repo):
+  """ Returns a Repository object representing the repo data model instance given. """
+  return Repository(
+    id=repo.id,
+    name=repo.name,
+    namespace_name=repo.namespace_user.username,
+    description=repo.description,
+    is_public=model.repository.is_repository_public(repo)
+  )