Added deadline timeout for socket operations (avoid deadlocks)

[vponomarev]

Current implementation will be blocked forever in case if haproxy (or someone else, opened this socket) will not generate any answer and will not close socket.

So, the fix is:

1. Presented new parameter TimeoutOp for operation timeout (separate from Timeout, used for connection timeout), now it will be possible to set Timeout = 10 (10 sec for connection) and TimeoutOp = 2 (2 sec for processing request).
2. Added SetDeadline for connection

I tested with fake haproxy running by: socat - UNIX-LISTEN:./var/run/haproxy.sock

Old implementation was blocked, new implementation returned after timeout: read unix ->/var/run/haproxy.sock: i/o timeout