Make init call on connections less heavy

[dsienkiewicz]

Problem
On Connection.init we start MainSocket process, wait arbitrary number of seconds and then start StreamingSocket process.
Both calls could fail, also adding explicit sleep is not a good job.
We should divide that process to have some kind of managing process, which will have a function to actually start new connection, thus adding both Main and Streaming processes to some well-known Supervisor.

Solution
Let's try to create one Supervisor for all connections, so it should be responsible for restarting them, wiring them up after Main connection is ready etc.
It's only a draft plan, should be expanded after further investigation.