Adds Network Interface Support for Control and Compute Nodes

Previously, the coe::network::interface class was only being
called for Swift proxy and storage nodes.  The class is also
needed for Compute and Controller nodes to manage the OVS bridge
interface.  Users can also extend the configuration to support
complex networking topologies beyond the scope of our reference
architectures.
Merge pull request #222 from CiscoSystems/network_interfaces

Adds Network Interface Support for Control and Compute Nodes