fixed  a bug in the router, when the peer is not exist exception was thrown instead of silent ingorning the message
fix from the original zeromq, releasing the sync object to avoid handle leak
fix from orginal zeromq, return eagain when pipe is full and madaory is set on a router
fixed a bug that zmq.poll run forever becausse the timeout was negative.
Merge pull request #44 from somdoron/master

Few bug fixes