pkg/testutils: utility functions to facilitate writing Go tests

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)
Add Cristian as maintainer to pkg/testutils

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)
Fix format in maintainers files

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)
Added note in manpages to clarify effect of docker start on started container

When run on a container that is already running, docker always succeeds.
This was an intentional change in v0.10; it previously caused an error.
This commit clarifies the man pages to indicate this is intended behavior.

Docker-DCO-1.1-Signed-off-by: Matthew Heon <mheon@redhat.com> (github: mheon)
Remove the API container struct and use env

This change touches docker logs, attach, and start -a along with get
exit code in the client.
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Rename nsinit package to namespaces in libcontainer
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Merge pull request #6204 from crosbymichael/no-structs

Remove the API container struct and use env
Initial links for Docker Hub rename

Docker-DCO-1.1-Signed-off-by: James Turnbull <james@lovedthanlost.net> (github: jamtur01)
Merge pull request #6205 from crosbymichael/rename-namespaces

Rename nsinit package to namespaces in libcontainer
Totally remove insert feature
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Adding initial version of C-based nsenter for allowing execin in
libcontainer.

Docker-DCO-1.1-Signed-off-by: Victor Marmol <vmarmol@google.com> (github: vmarmol)
Move env load to nsenter
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Exclude the user namespace for setns
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Merge pull request #1 from crosbymichael/nsenter-path

Move environment loading to nsenter
Merge pull request #6208 from crosbymichael/remove-insert

Totally remove insert feature
Move doc section in Remote API about removing insert from v1.11 to v1.12

Docker-DCO-1.1-Signed-off-by: Tibor Vass <teabee89@gmail.com> (github: tiborvass)
Merge pull request #6210 from tiborvass/fix_doc_remove_insert_remote_api

Move doc section in Remote API about removing insert from v1.11 to v1.12
Merge pull request #6026 from vmarmol/nsenter

Adding initial version of C-based nsenter for allowing execin in libcontainer.
pkg/units: Add FromHumanSize

This does the "reverse" of HumanSize, i.e. maps a string to an int64
using SI prefixes for the extension.

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
devmapper: Fail init with ErrNotSupported if simple devmapper call fails

If we can't even get the current device mapper driver version, then
we cleanly fail the devmapper driver as not supported and fall back
on the next one.

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)