Added logging to try to diagnose payment errors.
Trying something else to get log output on Heroku.

http://stackoverflow.com/questions/5994492/heroku-debugging
Still more payment logging.
Maybe logging by `puts` works?
Log via puts.

No patience to figure out why Rails.logger is not working.
Use billing zip code for credit card transaction.

Duh. Also, don't silently and without qualification `rescue` expressions
that can't under normal circumstances raise exceptions. (Not that I'm
fixing that right now.)
Removed log call that caused an error.