jenkins.yml repeatability

The `jenkins.yml` playbook can't run more than once against a single host, on account of #368. It's been annoying me for weeks. :bug: :no_entry_sign: 
> [jBCrypt](http://www.mindrot.org/projects/jBCrypt/) is a Java™ implementation of OpenBSD's Blowfish password hashing code

Yeah, that's what it looked like to me too. I just wasn't sure if this was providing someone a means to recover the password or that, even worse, that Jenkins' scheme (from the API) for auth took a raw hash.