Fixed error in group add example

There is no ${USERNAME} in bash, only ${USER}
fix error on docker wait
give more specific advice on setting up signing

Docker-DCO-1.0-Signed-off-by: Sven Dowideit <SvenDowideit@fosiki.com> (github: SvenDowideit)
Update release checklist with more information, more commands, and more correct flow (test, upload to test.docker.io, test, upload to get.docker.io, THEN tag&merge)

Docker-DCO-1.0-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Update Makefile to use "docker:GIT_BRANCH" as the generated image name for increased versatility

... and other minor Makefile improvements :)

Docker-DCO-1.0-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Fix a few miscellaneous typos (Unkown -> Unknown, Recieve -> Receive)

Docker-DCO-1.0-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Add more specific lvm2 version to PACKAGERS document

I personally tested this using our container, and this was the lowest version that compiles and runs properly.

Docker-DCO-1.0-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
google-compute-engine: fix typos
Revert "Make sure the cache lookup returns always the same result"

This reverts commit 1d4b7d8fa1af95ce83f263a49ed24e686fa7cb62.

Docker-DCO-1.0-Signed-off-by: Sjoerd Langkemper <sjoerd@byte.nl> (github: Sjord)
Fix issue #3375 - Return most recent image from the cache

ImageGetCached searches for an image from the cache. Instead of returning the
first image it finds, it should return the most recently created image. When a
build with --no-cache then adds a new image with the same parameters, it is
used instead of the old, existing image.

Docker-DCO-1.0-Signed-off-by: Sjoerd Langkemper <sjoerd@byte.nl> (github: Sjord)
Fix for #3345: Add Content-Type Header "application/json" to GET /version and /info responses in remote API

Docker-DCO-1.0-Signed-off-by: Manuel Woelker <github@manuel.woelker.org> (github: manuel-woelker)
Hello World: fix detach behavior

The hello world example relies on being able to exit the container attachment using Control-C without stopping it. According to this thread (and my own experience), this doesn't work anymore:

https://groups.google.com/forum/#!msg/docker-user/nWXAnyLP9-M/kbv-FZpF4rUJ

Added -sig-proxy=false to the attach command.
Fix registry pushing/tagging

* docker push host:port/namespace/repo wouldn't push multiple tags for
  the same image
* getImageList was unnecessarily complex returning a nested array of
  ImgData when a correctly ordered list of images was sufficient
* removed various bits of redundancy

Docker-DCO-1.0-Signed-off-by: Danny Yates <danny@codeaholics.org> (github: codeaholics)
Remove unneeded DependencyGraph

Docker-DCO-1.0-Signed-off-by: Danny Yates <danny@codeaholics.org> (github: codeaholics)
Further simplification

Docker-DCO-1.0-Signed-off-by: Danny Yates <danny@codeaholics.org> (github: codeaholics)
Fix indentation to match rest of file (tabs, not spaces)

Docker-DCO-1.0-Signed-off-by: Danny Yates <danny@codeaholics.org> (github: codeaholics)
gofmt

Docker-DCO-1.0-Signed-off-by: Danny Yates <danny@codeaholics.org> (github: codeaholics)
Add the customary bold
Merge pull request #3402 from manuel-woelker/3345-add-content-type-header-to-version-remote-api

Fix for #3345: Add Content-Type Header "application/json" to GET /version response in remote API
Merge pull request #3499 from tianon/typos

Fix a few miscellaneous typos (Unkown -> Unknown, Recieve -> Receive)