state -> status in App resource.
Style improvements to User resource.
Add userName field to User resource.
Update state param docs from WePay's API docs.

Because they said it better.
User.apply() -> User.find

This is more consistent with how we do things for the App resource.
Implement User.setCallbackUri.

The URI for this resource is /user/modify, but it's only used to set the
callback URI.
Style improvements to Account resource.