Implement option to provide a parent to monitor
Implement option to provide a parent to monitor

The couch_event_listener_mfa already had the necessary logic for
monitoring the parent process that spawned it for a start_link usage. In
some instances we have rexi_worker process use the enter_loop style APIs
to avoid the need to spawn a separate process. This just adds an option
`{parent, pid()}` that allows these processes to specify the parent to
monitor.

fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb