Protected Credit Card logging

We've added logging in two operations on `ProtectedCreditCard` object: `#save` and `#just_click_shop`. It is gonna save the given request data and the response from a SOAP call.

Once we put our hands on the logged operations from the production env, we will be able to reproduce the official XML response on the fake-braspag webservice.
@cassiomarques, any ideas? I'm also not sure of how sensitive this piece of data is.