Code: Implement handshake between arduino and pc

Description

As of now, we just attach the hardware interface to pc and let it run for a couple of seconds before running tests. Problem is that serial port gets flooded with old data (this issue got kinda resolved in 975e90f9 with waiting a second and then flushing IO buffers) I still however have a stash with draft of this handshake approach, it did not work at that time, but probably because I didn't try hard enough.