add mkimage support for mageia using urpmi

* host needs to be Mageia 4 or greater for docker kernel requirements
* Mageia 4 missing docker in repo, so install docker binary manually
* tested successfully installing Mageia versions 2, 3, 4 and cauldron (5)
Docker-DCO-1.1-Signed-off-by: Sam Bailey <sam@thatsamguy.com> (github:
thatsamguy)