Updated installation docs for CRUX as a Docker Host.

Docker-DCO-1.1-Signed-off-by: James Mills <prologic@shortcircuit.net.au> (github: therealprologic)
Update using_supervisord.md

changed the version of ubuntu to 13.04. In latest sshd will not work.
Merge pull request #6016 from ronsmits/patch-1

Update using_supervisord.md
Merge pull request #6006 from therealprologic/master

Updated installation docs for CRUX as a Docker Host.