add support for COPY to docker build

This adds a COPY command to docker build which works like ADD, but is
only for local files and it doesn't extract files.

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
Merge pull request #6090 from alexlarsson/fix-console

Fix /dev/console
Merge pull request #6067 from SvenDowideit/go-fmt-s

gofmt does not result in the same thing as go fmt -s, which is what travis uses
Merge pull request #5402 from SvenDowideit/dont-update-authors

Don't add yourself to the AUTHORs file - its generated
Merge pull request #6083 from bernerdschaefer/nsinit-drop-capabilities-after-changing-user

SETUID/SETGID not required for changing user
Handle EBUSY on remount

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
updated documentation for mentioning images vs containers

Docker-DCO-1.1-Signed-off-by: Robin Speekenbrink <robin@kingsquare.nl> (github: fruitl00p)

rebased by

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@home.org.au> (github: SvenDowideit)
Merge pull request #6099 from SvenDowideit/pr_out_updated_documentation_for_mentioning_images_vs_containers

updated documentation for mentioning images vs containers
docs/installation/google: update to use container-vm images

Docker-DCO-1.1-Signed-off-by: Johan Euphrosine <proppy@google.com> (github: proppy)

rebased by

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@home.org.au> (github: SvenDowideit)
Merge pull request #6100 from SvenDowideit/pr_out_docs_installation_google_update_to_use_container_vm_images

docs/installation/google: update to use container-vm images
* do not consider iptables' output an error in case of xtables lock
Docker-DCO-1.1-Signed-off-by: Giuseppe Mazzotta <gdm85@users.noreply.github.com> (github: gdm85)
Add ErrPrerequisites to improve misleading errors

There are two cases where we can't use a graphdriver:

1) the graphdriver itself isn't supported by the system
2) the graphdriver is supported by some configuration/prerequisites are
missing

This introduces a new error for the 2) case and uses it when trying to
run docker with btrfs backend on a non-btrfs filesystem.

Docker-DCO-1.1-Signed-off-by: Johannes 'fish' Ziemke <github@freigeist.org> (github: discordianfish)
Merge pull request #6098 from crosbymichael/retry-mount

Handle EBUSY on remount
Merge pull request #6106 from discordianfish/improve-error-btrfs-on-non-btrfs

Add ErrPrerequisites to improve misleading errors
Merge pull request #6105 from gdm85/master

Do not consider iptables' output an error in case of xtables lock
Added a new method cgroups.GetStats() which will return a cgroups.Stats object which will contain all the available cgroup Stats.
Remove old Stats interface in libcontainers cgroups package.
Changed Stats to use unit64 instead of int64 to prevent integer overflow issues.
Updated unit tests.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Merge pull request #6096 from vishh/stats_strongtype

Replaced fs.Stats() interface with fs.GetStats() which returns a cgroups.Stats strong type
Merge pull request #6048 from crquan/use-timeout-conn

Use Timeout Conn wrapper to set read deadline for downloading layer
block aufs on incompatible file systems

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
Merge pull request #6109 from unclejack/block_aufs_on_top_of_btrfs

block aufs on incompatible file systems