Correct 'ZMQ::Device.new' wrt. method signature

This method now takes the capture socket (if any)
as the third parameter, not the first.

https://github.com/chuckremes/ffi-rzmq/blob/master/lib/ffi-rzmq/device.rb
Merge pull request #437 from digitalronin/fix-msgqueue.rb

Correct 'ZMQ::Device.new' wrt. method signature