Better Testing

Depends on #14

Updates to all the testing machinery, including strainer, chefspec, and test kitchen. Also some code style fixes for foodcritic violations.

We don't need random test recipes in the cookbook proper anymore, because they can be loaded from testing/fake cookbooks in the test dir.

We also don't need a random Vagrantfile anymore because test-kitchen figures that all out for us. The Vagrantfile will be removed soon. We may still include a Vagrantfile in the testing cookbooks, because they represent examples of consuming infrastructure.