Improve VM shutdown for Sauce Labs connector
Improve VM shutdown for Sauce Labs connector

- Add retries for VM shutdown when talking to the API.
- Add 'ensure' to make sure the SSH connection is not reused.

final-ci/travis-worker,travis-ci/travis-worker,travis-ci/travis-worker,ireznice/travis-worker,ireznice/travis-worker,final-ci/travis-worker,gavioto/travis-worker,gavioto/travis-worker