Auto Redic/Mongo mount while rake spec

[DeTeam]

It'd be just handy to automatically setup Redis and Mongo server instances while trying to run tests.

[jnunemaker]

Thanks for the suggestion. We'll probably not tackle that but if a good pull request came in that did it, we would certainly take a look.

More likely I'll maybe split out the various backends from this repo so you can work on one backend at a time or make some way to do the same thing in only this repo.