registry: make certain headers optional

For a pull-only, static registry, there only a couple of headers that
need to be optional (that are presently required.
* X-Docker-Registry-Version
* X-Docker-Size
* X-Docker-Endpoints

Docker-DCO-1.1-Signed-off-by: Vincent Batts <vbatts@redhat.com> (github: vbatts)
registry: Info collection

roll version and standalone information into the _ping. And to support
Headers they are checked after the JSON is loaded (if there is anything
to load). To stay backwards compatible, if the _ping contents are not
able to unmarshal to RegistryInfo, do not stop, but continue with the
same behavior.

Docker-DCO-1.1-Signed-off-by: Vincent Batts <vbatts@redhat.com> (github: vbatts)
Added support for multiple endpoints in X-Docker-Endpoints header
Docker-DCO-1.1-Signed-off-by: Joffrey F <joffrey@docker.com> (github: shin-)
typo fix: 'methid' -> 'method'
Add missing blank lines in between list items

Lists with paragraphs as items need blank lines in between
items to generate correct layout.

Docker-DCO-1.1-Signed-off-by: Lance Chen <cyen0312@gmail.com> (github: Lance0312)
Created all manual pages in Markdown. Container for conversion.

Docker-DCO-1.1-Signed-off-by: William Henry <whenry@redhat.com> (github: ipbabble)

All Docker commands have a Markdown page.
Dockerfile used to build a Fedora based pandoc container.
md2man-all.sh is used inside the container.
README.sh includes an explaination on how to build the fedora/pandoc
          image and how to run the container directly.

 Changes to be committed:
	new file:   contrib/man/md/Dockerfile
	new file:   contrib/man/md/README.md
	new file:   contrib/man/md/docker-attach.md
	new file:   contrib/man/md/docker-build.md
	new file:   contrib/man/md/docker-commit.md
	new file:   contrib/man/md/docker-cp.md
	new file:   contrib/man/md/docker-diff.md
	new file:   contrib/man/md/docker-events.md
	new file:   contrib/man/md/docker-export.md
	new file:   contrib/man/md/docker-history.md
	new file:   contrib/man/md/docker-images.md
	new file:   contrib/man/md/docker-import.md
	new file:   contrib/man/md/docker-info.md
	new file:   contrib/man/md/docker-inspect.md
	new file:   contrib/man/md/docker-kill.md
	new file:   contrib/man/md/docker-load.md
	new file:   contrib/man/md/docker-login.md
	new file:   contrib/man/md/docker-logs.md
	new file:   contrib/man/md/docker-port.md
	new file:   contrib/man/md/docker-ps.md
	new file:   contrib/man/md/docker-pull.md
	new file:   contrib/man/md/docker-push.md
	new file:   contrib/man/md/docker-restart.md
	new file:   contrib/man/md/docker-rm.md
	new file:   contrib/man/md/docker-rmi.md
	new file:   contrib/man/md/docker-run.md
	new file:   contrib/man/md/docker-save.md
	new file:   contrib/man/md/docker-search.md
	new file:   contrib/man/md/docker-start.md
	new file:   contrib/man/md/docker-stop.md
	new file:   contrib/man/md/docker-tag.md
	new file:   contrib/man/md/docker-top.md
	new file:   contrib/man/md/docker-wait.md
	new file:   contrib/man/md/docker.md
	new file:   contrib/man/md/md2man-all.sh
Added a tag to FROM fedora (fedora:20)

Docker-DCO-1.1-Signed-off-by: William Henry <whenry@redhat.com> (github: ipbabble)
Update hack/make/ubuntu to use the new markdown-based manpages

This also removes all the old man pages, .gitignores their directory, and updates the md2man-all.sh script to be easier to read and more friendly to being called within hack/make/ubuntu.

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Edits based on ostezer's feedback.

Docker-DCO-1.1-Signed-off-by: William Henry <whenry@redhat.com> (github: ipbabble)
Made some edits and removed the alternative, manual generation instructions.

Docker-DCO-1.1-Signed-off-by: William Henry <whenry@redhat.com> (github: ipbabble)

 Changes to be committed:
	modified:   contrib/man/md/README.md
Fixed a sentence for ostezer.

Docker-DCO-1.1-Signed-off-by: William Henry <whenry@redhat.com> (github: ipbabble)

	modified:   contrib/man/md/README.md
Edits based on Sven's comments.

Docker-DCO-1.1-Signed-off-by: William Henry <whenry@redhat.com> (github: ipbabble)

 Changes to be committed:
	modified:   contrib/man/md/docker-build.md
	modified:   contrib/man/md/docker-commit.md
Further edtis based on comments.

Docker-DCO-1.1-Signed-off-by: William Henry <whenry@redhat.com> (github: ipbabble)

 Changes to be committed:
	modified:   contrib/man/md/README.md
	modified:   contrib/man/md/docker-build.md
	modified:   contrib/man/md/docker-cp.md
	modified:   contrib/man/md/docker-logs.md
	modified:   contrib/man/md/docker-push.md
Changed Image to image.

Docker-DCO-1.1-Signed-off-by: William Henry <whenry@redhat.com> (github: ipbabble)

 Changes to be committed:
	modified:   contrib/man/md/README.md
Merge pull request #5323 from Lance0312/docs-missing-blank-lines

Merged.
Freeze server/server.go for deprecation

* Add notice in server/server.go explaining not to add stuff there, and
what to do instead.

* Make myself a sole maintainer of server/ to avoid concurrent edits
while refactoring.

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)
Merge pull request #5334 from shykes/freeze-server

Freeze server/server.go for deprecation
Clean up MAINTAINERS files

* Remove out of date "vacation mode"
* Fix my email address
* Remove infrastructure maintainers to reflect reality (core maintainers
are currently maintaining their own infrastructure).

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)
Merge pull request #5331 from shykes/cleanup-maintainers

Clean up MAINTAINERS files
Merge pull request #5205 from ipbabble/manpages

Completed the manual paged in Markdown. rm old man pages.