Fukász Rómeó Ervin / cloud

Feature Virtio

Enhance CIRCLE to use virtio-serial ports to communicate with the agent.

 WARNING 

Requires (virtio branch):
 agentdriver
 vmdriver

Tests:
* new-windows agent    (Working virtio with update watchdog for service restart)
* new-linux agent 
* legacy-windows agent  (Old windows agent can't update)
* legacy-linux:   Working update with less than 16k tar

See merge request !205