check if the daemon is run as root on startup

This commit makes Docker throw an error if the daemon isn't started as
root.

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
update AUTHORS

Docker-DCO-1.1-Signed-off-by: Bryan Matsuo <bryan.matsuo@gmail.com> (github: bmatsuo)
FIXES #5398: pkg/graphdb build only dependent on cgo tag

Docker-DCO-1.1-Signed-off-by: Bryan Matsuo <bryan.matsuo@gmail.com> (github: bmatsuo)
remove when httputil.NewClientConn when not in hijack

Docker-DCO-1.1-Signed-off-by: Victor Vieux <vieux@docker.com> (github: vieux)
cli.md: Fix up Markdown formatting by adding one `
move hijack to it's own file

Docker-DCO-1.1-Signed-off-by: Victor Vieux <vieux@docker.com> (github: vieux)
Don't restrict lxc because of apparmor

We don't have the flexibility to do extra things with lxc because it is
a black box and most fo the magic happens before we get a chance to
interact with it in dockerinit.
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
fix https

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

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

Docker-DCO-1.1-Signed-off-by: Victor Vieux <vieux@docker.com> (github: vieux)
cli.md: sudo at the right place

Docker-DCO-1.1-Signed-off-by: Felix Rabe <felix@rabe.io> (github: felixrabe)
return write error

Docker-DCO-1.1-Signed-off-by: Victor Vieux <vieux@docker.com> (github: vieux)
engine: catchall handler is shadowed by specific handlers

This allows using `Engine.Register` and `Engine.RegisterCatchall` on the
same engine without the catchall hiding all other handlers.

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)
Engine: empty job names are illegal, catchall or not

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)
cli.md: More typos

I've seen one other missing space that I addressed in another PR already.
I don't know whether that is a common occurrence in the docs.

About the second diff chunk, it looks like some copy-paste mistake to me.

Docker-DCO-1.1-Signed-off-by: Felix Rabe <felix@rabe.io> (github: felixrabe)
run.md: Convert some backticks to apo's
Merge pull request #5556 from crosbymichael/no-restrict-lxc

Don't restrict lxc because of apparmor
run.md: Close braces

Docker-DCO-1.1-Signed-off-by: Felix Rabe <felix@rabe.io> (github: felixrabe)
Move 'auth' to the registry subsystem

This is the first step towards separating the registry subsystem from
the deprecated `Server` object.

* New service `github.com/dotcloud/docker/registry/Service`
* The service is installed by default in `builtins`
* The service only exposes `auth` for now...
* ...Soon to be followed by `pull`, `push` and `search`.

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)
Move 'search' to the registry subsystem

This continues the effort to separate all registry logic from the
deprecated `Server` object.

* 'search' is exposed by `github.com/dotcloud/docker/registry/Service`
* Added proper documentation of Search while I was at it

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)