Description of problem:
If you deploy the overcloud with --neutron-tunnel-types vxlan, but you don't specify the --neutron-network-type, then you end up with an unusable network configuration on the overcloud. All of the OVS agents are configured for VXLAN, but the Neutron networks are GRE, so nothing can communicate.

Version-Release number of selected component (if applicable):
puddle-2015-07-17.2

How reproducible:
100%

Steps to Reproduce:
1. Deploy with --neutron-tunnel-types vxlan but do not specify the --neutron-network-type
2.
3.

Actual results:
Neutron networks are configured as GRE, but the OVS agents are configured for VXLAN tunneling.

Expected results:
The CLI should throw an error if the --neutron-network-type does not match at least one of the --neutron-tunnel-types.

Additional info: