Automate testing 577

@wallrj and I have experimented with modifying parts of the docs to use wordish.

Also, there is a start of running wordish from trial.

However, what we would like looked at are the issues, as specified in release-process.rst. We think that a reasonable amount of modification would have to be done to wordish to support even our most basic use case (having the engineer install everything, and start up the VMs and only test the outputs of `docker ps` after running `flocker-deploy` multiple times).

We won't catch many regressions with this using wordish's system of putting '...' all over the place, and it would make the documentation much less readable. We would like feedback on the importance of these tests, given how much work it might take, and perhaps feedback on which problems to solve first.

If we are going to go down the wordish route, I don't think that it is a small job and I'm not sure whether it should be a priority at this time.
We can pass a custom prompt to the `wordish.ShellSessionParser`. See:
 * https://github.com/ClusterHQ/flocker/pull/709/files#diff-d258c55143eec3628ec38eca453009aeR20