Initial eavesdrop command/module commit
run eavesdrop via freeswitch:sendmsg instead of freeswitch:api
update contributors
group eavesdrop's calls together
run `eavesdrop` & `call_pickup` using `prepare_app`
KAZOO-2447: move common function to cf_util
KAZOO-2447: use cf_util for common functions

handle when approved_group_id is set

handle channel_destroy event
KAZOO-2447: use cf_util for common functions

formatting and some simple refactoring
KAZOO-2447: formatting and style updates
Merge branch 'siplabs-KAZOO-2447'