Networking between VMs: Improve Migration Throughput (use Tap devices, or another quicker solution)

[phip1611]

The current setup for networking between ControllerVM & ComputeVM is very slow. @tpressure measured 30mbit/s instead of 700mbit/s which he measured in a PoC using tap devices.

[phip1611]

@tpressure also has a PoC where we are using normal sockets which also significantly improved throughput