Use an appropriate filter when waiting connection with kqueue.

I started using meinheld with **the socket patch** but it does'n work.
I tested it with my django project in FreeBSD(9.1RELEASE) and OSX(10.8.5).
It seems that sockets doesn't respond in some cases.
So, I re-tested it with example/patch/urllib2_sample.py and I found that no events occurred after finishing a  connection in meinheld.msocket.internal_connect().
[This article](http://forums.freebsd.org/showthread.php?p=232637) refers to the kevent, should subscribe the event with EVFILT_WRITE when waiting for a connection.
I fixed msocket.py according to it and it seems to work fine.

Thanks