of_01: Improve error logging on socket bind failure

I actually have absolutely no idea what I was thinking with some of the
previous version of this code from 065f5f4724 and #62.  It kind of looks
like I half-finished it and called it done or something.  Hopefully this is
an improvement.
tests: Make __init__ work without core

As previously referenced, I am not sure this file actually does anything
useful anyway.
ioworker: Fix socket connections on Linux

Apparently when a socket connects, Linux marks a socket as ready to
receive and then returns EAGAIN on a zero-length read.  This seems to be
similar to the Windows behavior, and we now treat them the same way.

This should fix a problem reported by github user xdhanz.