Added zmq receiver module

This module is to configure openstack zmq receiver.

Todo
Documentation to be completed
Tests to be added
Basically for cinder-volume it make two sets of configurations,

1. json entry for all cinder-volume nodes
2. individual json entries for each cinder-volume nodes like cinder-volume:<node name>

basically in getter code, I am getting array of nodes in entry (1) using "res" and return that array. In case of cinder-volume, getging array of nodes in entry (2) using res1 and make an intersection of both array and return that array (intersection of res and res1). 
This handle the situation where discrepancy on entry (1) and 2. e.g entry 1 has both oc1 and oc2 but entry 2 only have oc2 and vice versa.