Update docker container host files, when no SSH is available

[ProxiBlue]

Hello,
not an issue, but noting here as other can find of use:

The plugin assumes all containers will have SSH. With docker this is not a reality.
I created a new docker communicator, which uses the docker API to effect all the needed SSH commands to docker instances, which then effectively makes this work with any docker based container.

(tested in Linux only)

https://github.com/ProxiBlue/vagrant-communicator-docker