New Network resource to define standard network topology

Neutron resources allow to work on low level with Neutron network configuration, but it puts a lot of burden to the end user who need to specify and bind all these low level parameters. It will be great to have a single resource which can create a bunch of low level resources and provide an information about available network resources. This new resource should have discovery mechanism to find existing Neutron resources provisioned by admins. The example is an external network which is usually created and managed by admins.