Add ETag to module HTTP response.
Add ETag to module HTTP response.

honestegg/cassette,BluewireTechnologies/cassette,andrewdavey/cassette,andrewdavey/knapsack,honestegg/cassette,andrewdavey/cassette,honestegg/cassette,damiensawyer/cassette,damiensawyer/cassette,damiensawyer/cassette,andrewdavey/knapsack,BluewireTechnologies/cassette,andrewdavey/knapsack,andrewdavey/cassette