Fixes Authorization and Person creation and speeds up tests.

Authorization::sanitize_params now works like Person::sanitize_params.
That is, it returns a Hash with only permitted symbol (interned) keys.

Person::new_local now saves the associated feeds because they were
otherwise lost. It stores the ids in the actual keys mongo is using.

Authorization tests were slow when Authorizations were created. I
removed the stubs for clarity and moved the stubs for RSA key generation
up where they should have been.

The tests now make use of the Authorization's domain key. I'm using
www.example.com to make sure there is a subdomain in testing.