Implements Nova FloatingIP resources

    https://blueprints.launchpad.net/heat/+spec/nova-networking-floatingip

This code aims to add support OS::Nova::FloatingIP
and OS::Nova::FloatingIPAssociation in Heat.

Change-Id: I678f8a099b97c0fb46bf1056203fc9bafe3032aa
Implements: blueprint nova-networking-floatingip
Merge "Implements Nova FloatingIP resources"