Test Neutron host routes and gateway

This commit adds a script that tests the host routes and gateway functionallity
in Neutron. Along the way, it tests the behavior of the Neutron API for
networks, subnets and ports.

This test is part of phase II of the 'Exposing Neutron' project.

The scenario implemented is described in:

https://one.rackspace.com/display/cloudqe/Exposing+Neutron+Test+Strategy#ExposingNeutronTestStrategy-PhaseIIscenariotests

Change-Id: Ie9e4d94b390f1f79bf6d9ed0d932605fd4354b99
Merge "Test Neutron host routes and gateway"