Add bash completion for `docker-machine provision`
Add bash completion for `docker-machine provision`

Signed-off-by: Harald Albers <64b2b6d12bfe4baae7dad3d018f8cbf6b0e7a044@albersweb.de>

ibuildthecloud/machine,dgageot/machine,exoscale/docker-machine,docker/machine,voutilad/machine,SvenDowideit/machine,dgageot/machine,londoncalling/machine,dweomer/docker-machine,voutilad/machine,SvenDowideit/machine,Herbis/machine,ibuildthecloud/machine,dweomer/docker-machine,Herbis/machine,londoncalling/machine,docker/machine,exoscale/docker-machine