Option to write logs to syslog

[rsyring]

I'd really like to see an option that would cause gathered data to also be written to syslog. In our case, we write everything to syslog and then forward syslog to a log aggregator. So this would be a great way to get success messages into a place that they can be reviewed if needed while also getting Sentry alerts for known errors.

Bonus points for an option to log as JSON:

cron-sentry --syslog ...
# same as the above
cron-sentry --syslog=plain
# log as json
cron-sentry --syslog=json

If you are interested in this option, I could most likely submit a PR that does the heavy lifting.