KAZOO-1631: store the gather sub-action process
KAZOO-1631: add arbitrary event handler pids to relay amqp messages to as well
KAZOO-1631: process sub actions serially, and kill the sub process on first DTMF recvd
KAZOO-1631: pass optional function to call on first DTMF reception
KAZOO-1631: add new process to pivot_call's event handlers list
KAZOO-1631: tickies and formatting
Merge pull request #159 from 2600hz/KAZOO-1631

Kazoo 1631