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.
Add specific branch of jpetazzo's busybox to clone from so we can assume nice things about it

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Simplify "adduser" in the Dockerfile to use the more scripting-friendly "useradd"

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Added stats.go which provides strong types for all stats that will be exported by libcontainer. This commit only introduces the strong type.
Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Merge pull request #6019 from tianon/update-dockerfile-busybox

Add specific branch of @jpetazzo's busybox to clone from so we can assume nice things about it
now busybox as nc

Docker-DCO-1.1-Signed-off-by: Victor Vieux <vieux@docker.com> (github: vieux)
Add check for iptables xlock support
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Merge pull request #6022 from crosbymichael/iptables-wait

Add check for iptables xlock support
Merge pull request #6018 from vishh/stats_strongtype

Strong type all stats exported by libcontainer
Merge pull request #6020 from vieux/update_test_remove_nc_bind_mount

now busybox as nc
docs/reference/builder: fix USER doc

Docker-DCO-1.1-Signed-off-by: Johan Euphrosine <proppy@google.com> (github: proppy)
Merge pull request #6023 from proppy/patch-4

docs/reference/builder: fix USER doc
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.
Some fixes to the Intro pages

Docker-DCO-1.1-Signed-off-by: James Turnbull <james@lovedthanlost.net> (github: jamtur01)
Merge pull request #6001 from jamtur01/introfixes

Some fixes to the Intro pages
Use Timeout Conn wrapper to set read deadline for downloading layer

This fixed first part of #6024

Docker-DCO-1.1-Signed-off-by: Derek <crq@kernel.org> (github: crquan)