External YANET API bindings

[GeorgyKirichenko]

YANET uses a proprietary binary protocol to communicate between DataPlane, ControlPlane and CLI. There is also a cli utility that allows one to manage YANET using the command line.
There is also a family of load balancer functions described by the protobuf protocol, any other API can only be called by marshaling the arguments into the cli execution and then parsing the stdout back.
The basic idea is to implement at a minimum the API provided by cli using the protobuf protocol description, which allows managed code to be generated using any language that supports this protocol.