Add MTU to lxc conf to make host and container MTU match

If you are using jumbo frames the host side of the veth was being set to
1500.  Docker would set the MTU of the container side of the veth to 9001.
This would lead to a situation in which the two sides of the veth had
different MTU sizes causing issues in network traffic.

Docker-DCO-1.1-Signed-off-by: Darren Shepherd <darren.s.shepherd@gmail.com> (github: ibuildthecloud)
seperate out the terminal functions from lxc to the pkg/term

  Since these functions are indepenent of lxc, and could be used by
  other drivers.

Docker-DCO-1.1-Signed-off-by: Vincent Batts <vbatts@redhat.com> (github: vbatts)
Move the terminal setup to execdriver, instead of ./pkg/term

  It is independent of any particular driver, but likely used by
  multiple execdrivers. Also, pkg/... is not to have any links to
  docker, which this terminal setup does.

Docker-DCO-1.1-Signed-off-by: Vincent Batts <vbatts@redhat.com> (github: vbatts)
Engine: cleanup side effects between tests

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)
Engine: builtin command 'commands' returns a list of registered commands

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)
Adjust kernel version parsing to be more lenient of strange things like "3.12-1-amd64"

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
help contributors be more productive

certainly saved me time after I found this in hack/make.sh :)

Docker-DCO-1.1-Signed-off-by: Tim Ruffles <oi@truffles.me.uk> (github: github_handle)
fix divide by zero error

Docker-DCO-1.1-Signed-off-by: Victor Vieux <victor.vieux@docker.com> (github: vieux)
correcting the package name for the terminal setup

Docker-DCO-1.1-Signed-off-by: Vincent Batts <vbatts@redhat.com> (github: vbatts)
Merge pull request #4314 from shykes/engine-commands

Engine: builtin command 'commands' returns a list of registered commands
Convert api/server.go to also use the handy user package

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Merge pull request #4335 from tianon/what-the-etc-group

Convert api/server.go to also use the handy user package
Rewrite docker rmi

Docker-DCO-1.1-Signed-off-by: Victor Vieux <victor.vieux@docker.com> (github: vieux)
bump API version

Docker-DCO-1.1-Signed-off-by: Victor Vieux <victor.vieux@docker.com> (github: vieux)
:= / var

Docker-DCO-1.1-Signed-off-by: Victor Vieux <victor.vieux@docker.com> (github: vieux)
fix tests

Docker-DCO-1.1-Signed-off-by: Victor Vieux <victor.vieux@docker.com> (github: vieux)
fix message 'No such image: ubuntu' => 'No such image: ubuntu:latest'

Docker-DCO-1.1-Signed-off-by: Victor Vieux <victor.vieux@docker.com> (github: vieux)
fix doc

Docker-DCO-1.1-Signed-off-by: Victor Vieux <victor.vieux@docker.com> (github: vieux)
fix bad rebase

Docker-DCO-1.1-Signed-off-by: Victor Vieux <victor.vieux@docker.com> (github: vieux)
add missing doc

Docker-DCO-1.1-Signed-off-by: Victor Vieux <victor.vieux@docker.com> (github: vieux)