Add a network ports IP mapping resource

Add a network ports IP mapping resource

This patch adds a resource which constructs a Json output
parameter called net_ip_map which will allow us to easily
extract arbitrary IP addresses for each network using the
get_attr function in heat.

The goal is to use this data construct in each role
template to obtain the correct IP address on each
network.

Change-Id: I1a8c382651f8096f606ad38f78bbd76314fbae5f