Removed unnecessary pauses

- there should be no need to sleep before receiving messages
- the sleep makes selftesting obnoxiously slow
Message parsing was broken

- discarded routing_id when reading from ZMQ_ROUTER
- simplified _recv and _recv_wait methods
- properly collect routing_id in _decode method
- added selfcheck test on routing_id
Merge pull request #25 from hintjens/master

Fixed message parsing