Configurable logrotate for server and beaver

I didn't realize that lusis#119 only covered the agent recipe. I've made the logrotate options configurable in server and beaver.

I also made the postrotate command configurable. We are using monit to manage the beaver service and it does not appreciate having the PID changed by logrotate. Using copytruncate may remove the need to do a force-reload at all, however.