Simplify the version generation and fix dirty builds appearing after first make (helps #62)
Draft implementation of logstash gem generation and publication (Fixes #60)
Improved version patching
Print ZMQ version information in logs
Make develop version compatible with older rubygems versions, specifically v1.8
Update change log
Fix zmq_3_x build (towards #63)
Graceful exit if using zmq transport with libzmq <= 4