Added socket keepalive, for long running processes

Hi

I have noticed that when rpyc is running a long running process remotely >2hrs, that eventually since the socket is idle for so long it is disconnected. By adding keepalive sockopt it is possible to keep the connection despite the long running process. 

I have made the changes to the stream.py
The other two files changes was just me trying to figure out git again.

Terence