Add logging messages for spam messages

The bayesian classifier will now log certain probabilities for messages
marked as spam. The upshot of this is that now we can piece together why a
message is being marked as spam.
Small fixes

1. Log to a file instead
2. Print the word as opposed to its values
3. Delete a copy paste error
Use a logger and format logging in one go

Also don't log conditionally, log everything.
Fix formatting in report script

This really should have gone in the py26 fixes branch, but I didn't get it done
in time. It's a bunch of really simple formatting errors which differ in
python 2.6 and 2.7.
Logging simplification and flake8  pass
Merge pull request #28 from iankronquist/bayes-logging

Bayes logging