Make logging cloud-friendly

[alxmrs]

Log statements are currently written to a file. If the bot is deployed to a VM instance, it will eventually run out of disk space.

Ideally, logs should be treated as event streams. Also, it'd be nice to use pythons standard log library.

[mtingers]

Logging does need more options. For the most part, stdout/stderr logging covers things like systemd and containers, but might not be ideal for some setups. I propose:

1. stdout is always on (see: Python's logging StreamHandler)
2. Optional configuration for a log handler mapped to Python's handlers. Examples:
   • simple for WatchedFileHandler
   • rotate_time for TimedRotatingFileHandler
   • rotate_size for RotatingFileHandler

Configuration could look something like:

[logging]
# simple | rotate_time | rotate_size
handler = rotate_size
filename = /path/to/logfile.log
max_bytes = 104857600
backups = 10