[WIP] SOC_U: Implemented some socket functions

This allows ftpony and ftbrony to work.
It's using Berkeley sockets directly since that's what the soc:U service exposes to applications.

Still WIP.
I would feel more comfortable with creating a structure + object pool to hold the socket. This would be more expansible and also allow you to bundle the blocking flag in the struct, avoiding that other map workaround. This can be refactored later, just something to thing about.