Add raven-release instance initializer
Add raven-release instance initializer

This ensures that we are syncing the release information we are sending to sentry
with what Waiter is configured to create on successful deploys

travis-ci/travis-web,travis-ci/travis-web,fotinakis/travis-web,fotinakis/travis-web,travis-ci/travis-web,travis-ci/travis-web,fotinakis/travis-web,fotinakis/travis-web