Proxy TCP traffic to/from Miner via Hub

[noxiouz]

Now Miner has multiplexed TCP connection to a Hub. We can use extra channels to proxy TCP traffic to/from the miner via Hub

Steps for naive solution:

• Miner should detect NAT (look at #15)
• If the miner needs proxy, the hub should listen a port, patch returned values to a CLI
• when accept returns a connection, open new stream in the conn to Miner
• transfer traffic through it.
• all open listeners must be bound to a miner's context and task inside Hub to be properly disposed.
• miner must transport actual info about lauched tasks

Suggested optimizations for naive userspace proxy solution:

• do not send traffic from miner via hub. Just dance around src packet address (like tunnel IPvS)