Debian packaging:  Add missing python deps

Add `machinekit` package
`Depends: python-zmq, python-protobuf, python-gst0.10`

Reported by Janos Bujtar
https://groups.google.com/d/msg/machinekit/TvdphT-tzws/nrOA3giR3YwJ
Merge pull request #325 from zultron/missing-deps

Debian packaging:  Add missing python deps