Fixes #3879 by updating embedding of ascii.io (now asciinema.io)
Docker-DCO-1.1-Signed-off-by: Andy Rothfusz <github@developersupport.net> (github: metalivedev)
docker: detect defaultNetworkMtu from default route

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

Docker-DCO-1.1-Signed-off-by: Johan Euphrosine <proppy@google.com> (github: google)
docker/config: update -mtu flag default

Docker-DCO-1.1-Signed-off-by: Johan Euphrosine <proppy@google.com> (github: google)
docs/cli: add mtu option

Docker-DCO-1.1-Signed-off-by: Johan Euphrosine <proppy@google.com> (github: google)
Updated width to 815 per comment.
Docker-DCO-1.1-Signed-off-by: Andy Rothfusz <github@developersupport.net> (github: metalivedev)
Vagrantfile port forwarding usages documented. Added usage via envvar FORWARD_PORTS for custom port or list of comma-separated ports
Docker-DCO-1.1-Signed-off-by: Keyvan Fatehi <keyvanfatehi@gmail.com> (github: keyvanfatehi)
Merge pull request #3883 from metalivedev/fix-3879

Fixes #3879 by updating embedding of ascii.io (now asciinema.io)
Do not call Put twice and do not call it on defer

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Fix unmounts out of container export funcs
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Merge pull request #3188 from keyvanfatehi/vagrant-port-forwarding-list

Vagrantfile port forwarding made more flexible (w/ comments)
Merge pull request #3887 from proppy/detect-network-mtu

docker: detect defaultNetworkMtu from default route
Merge pull request #3915 from crosbymichael/no-double-put

No no put put