update gem version in gemfile.local
Updating ext to always do make on compile - allows testing changes to zmq/czmq in place without having to run configure each time.
ZMQ::Context fix for destroying a context in a child process inherited by fork()

Also ensures that contexts can only be used by the process that created them.
Updating readme
Merge pull request #23 from mattconnolly/master

Fix Process.fork() child process termination destroying parent's context