chore(registry): bump version to v0.8.1
test(registry): remove unit tests

the unit tests are outdated, useless and consistently failing. We were
cloning and running the unit tests correctly some months ago, but now
it requires a local redis. Unit tests are covered by
docker/docker-registry, anyways.
Merge pull request #1838 from bacongobbler/bump-registry

chore(registry): bump version to v0.8.1