Integration testing from the CLI

I started playing with the [aruba cucumber](https://github.com/cucumber/aruba) gem because I wanted an end-to-end integration test in place before I tried to do any more refactoring, started adding new features, or upgrading gems.

Originally, I was going to just keep these test in my local repo but then I consider that its going to be fiddly to keep things in sync, and it would be nice to have the tests running on Travis.

If you would like to try running the cucumber tests locally you should be able to do it with:
```
bundle install
bundle exec rake features
```

If you interested in merging the commits, let me know and I will try to get all of the test running with Travis first.

Additionally, I can give try getting aruba running in minitest again. The cucumber is not too complicated at this stage, but I know that it was not something that you were looking to add to the project.