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.

endpoints/v2/tag.py

@@ -5,6 +5,7 @@ from endpoints.common import parse_repository_name
 from endpoints.v2 import v2_bp, require_repo_read, paginate
 from endpoints.v2.errors import NameUnknown
 from endpoints.decorators import anon_protect
+from data.interfaces import v2
 
 @v2_bp.route('/<repopath:repository>/tags/list', methods=['GET'])
 @parse_repository_name()