- do something about state_id / state_id_state (linkpoint, freeside) vs.
  license_num / license_dob (authorize.net, docs here).  wtf!
- Use Net::HTTPS::Any
- hmm... requires HTTP::Headers v1.59
- move revmap_fields into the base class
- remap_fields: Not the cleanest thing to mix up our namespace with the
  processor-specific names.
- Define a better model of exception handling that doesn't involve dying on
  some things.