Add support for docker variables

[abel408]

Please let me know if this already exists. I could not find anything in the documentation about adding variables to a docker run command when creating a docker container with mist.io. For example, I have created a docker network and would like my container to use that network. If I am creating this docker container from shell, it would look like this "docker run --net=docker_lan --ip=10.10.10.5 -idt ubuntu". I would like the ability to pass variables like this one to the docker container in mist.io.