Add support for `RUN [""]` in Dockerfiles for greater specificity in what is actually executed

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Add failing test for odd kernel version

Docker-DCO-1.1-Signed-off-by: Charles Lindsay <chaz@chazomatic.us> (github: chazomaticus)
Remove Flavor from KernelVersionInfo

Also change to parsing it with regexp to keep things simple.

Docker-DCO-1.1-Signed-off-by: Charles Lindsay <chaz@chazomatic.us> (github: chazomaticus)
Fix apparent typo

Docker-DCO-1.1-Signed-off-by: Charles Lindsay <chaz@chazomatic.us> (github: chazomaticus)
Use Sscanf instead of regexp

Docker-DCO-1.1-Signed-off-by: Charles Lindsay <chaz@chazomatic.us> (github: chazomaticus)
Re-add Flavor to KernelVersionInfo

Docker-DCO-1.1-Signed-off-by: Charles Lindsay <chaz@chazomatic.us> (github: chazomaticus)
Re-add kernel Flavor tests

Docker-DCO-1.1-Signed-off-by: Charles Lindsay <chaz@chazomatic.us> (github: chazomaticus)
Add a --signal option to the kill command to specify a signal.

Docker-DCO-1.1-Signed-off-by: Paul Lietar <paul@lietar.net> (github: plietar)
Grammar and punctuation fixes

Docker-DCO-1.1-Signed-off-by: John Gardiner Myers <jgmyers@proofpoint.com> (github: johngmyers)
Wording improvements

Docker-DCO-1.1-Signed-off-by: John Gardiner Myers <jgmyers@proofpoint.com> (github: johngmyers)
change the documentation only - It looks like we have a number of cmdline params to completely update from the code version

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@home.org.au> (github: SvenDowideit)
Add comment about ignoring Sscanf error

Docker-DCO-1.1-Signed-off-by: Charles Lindsay <chaz@chazomatic.us> (github: chazomaticus)
Merge pull request #3695 from chazomaticus/3628-ignore-kernel-flavor

ignore non-numeric characters when parsing kernel version
Merge pull request #3682 from alexlarsson/implement-tar

Implement tar in Go
Merge pull request #3712 from plietar/kill-signal

Add a -s option to the kill command to specify a signal.
Merge pull request #3073 from alexlarsson/refcount-driver-mounts

Refcount driver mounts
Merge pull request #3558 from tianon/buildfile-run-json

Add support for RUN [""] in Dockerfiles
Merge pull request #3713 from SvenDowideit/document-bind-mount-file

bind mounts work for files - give an example, as its very very useful.
Merge pull request #3716 from johngmyers/patch-1

Grammar fixes and wording improvements
Add experimenta btrfs driver

This is an experimental btrfs driver. To use it you must have
/var/lib/docker mounted on a btrfs filesystem and explicitly
specify DOCKER_DRIVER=btrfs in the docker daemon environment.

It works by using subvolumes for the docker image/container layers.

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