KAZOO-3116 initial

Callback feature
Variables should be "camel-cased", so `CallId` over `CALLID` in this case. Also, drop the list terminator `]` to a new line (along with `}])` to a new line as well. You can see an example [here](https://github.com/2600hz/kazoo/blob/master/applications/jonny5/src/jonny5_listener.erl#L33-36)