"Tokenize a card without a secret" works.

There's a teeny bit of extra infrastructure to get a token. I built it by
accident, but we'll need it eventually, so I just left it in.
Set up rake tasks to make running features easier

Two things here:

1. I'm going to translate features over, and mark them as failing when
they are failing. I'll also tag them with gh-N to mark GitHub issue #N
that they go along with.
2. 'rake cruise' has been set up to run for CI. Basically, it runs all
the things that aren't failing, and makes sure they pass. Then, it runs
all thet hings that are supposed to be failing, and makes sure they
fail. If either of those are not true, it fails the build, and if
they both pass, they pass. This way we know when something starts
passing again, and to remove the failing tag.
New feature: creating API keys.

There was no existing schemas for the API key response, so I made one.
New feature: retrieve API keys
New feature: list all API keys
New feature: remove API keys
Refactor/reorganize steps for clarity.

It's important not to refactor steps _too_ much, but these were certainly
http steps and not card steps.