Add docker::run::privileged flag to allow granting extra privileges to containers

This adds support for running containers with extra privileges by passing the "--privileged" flag. Docs: http://docs.docker.io/reference/run/#runtime-privilege-and-lxc-configuration 

"When the operator executes docker run --privileged, Docker will enable to access to all devices on the host as well as set some configuration in AppArmor to allow the container nearly all the same access to the host as processes running outside containers on the host. Additional information about running with --privileged is available on the Docker Blog."