registry: Fixed a bug where token and cookie info wouldn't be sent when using LookupRemoteImage(). Fixed a bug where no error would be reported when getting a non-200 status code in GetRemoteImageLayer()
Mock registry: Fixed a bug where the index validation path would return a 200 status code instead of the expected 204
New registry unit tests remade from scratch, using the mock registry
Merge branch 'registry_test' of https://github.com/dotcloud/docker into registry_test

Conflicts:
	registry/registry_mock_test.go
gofmt