Unify logging

[flipmcf]

when in production using gunicorn, there are files:
'casterpak.access.log'
'casterpak.error.log'
'casterpak.log'

I think casterpak.log is created by the cleanup task.

cleanup should log to the 'error' log, and maybe we should call the 'error' log 'casterpak.log' . A separate access log is fine and some users may like that. But 3 logfiles is just too much.