Minor updates and fixes to the CONTRIBUTING doc

* Fixed some uses of docker v. Docker
* Formatting and line wrapping.
* Spelling errors and grammar fixes.

Docker-DCO-1.1-Signed-off-by: James Turnbull <james@lovedthanlost.net> (github: jamtur01)
update vendored archive/tar to lower allocations

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
Relax dns search to accept empty domain

In that case /etc/resolv.conf will be generated with no search
option. Usage: --dns-search=.

Docker-DCO-1.1-Signed-off-by: Fabio Falci <fabiofalci@gmail.com> (github: fabiofalci)
Update README.md

Docker-DCO-1.1-Signed-off-by: Hyeongkyu Lee <hyeongkyu.lee@navercorp.com> (github: leeplay)
docker save: fix the 'repositories' file

For various use cases, the 'repositories' file does not match expected
behavior.

Like,

	docker save busybox:latest | tar t

Before:

	[...]
	busybox:latest/
	busybox:latest/VERSION
	busybox:latest/json
	busybox:latest/layer.tar
	# note, the layer name, and lack of 'repositories' file

Now:

	[...]
	a9eb172552348a9a49180694790b33a1097f546456d041b6e82e4d7716ddb721/
	a9eb172552348a9a49180694790b33a1097f546456d041b6e82e4d7716ddb721/VERSION
	a9eb172552348a9a49180694790b33a1097f546456d041b6e82e4d7716ddb721/json
	a9eb172552348a9a49180694790b33a1097f546456d041b6e82e4d7716ddb721/layer.tar
	repositories
	# and the repositories file is correct for the single tagged
	# image.
	#> {"busybox":{"latest":"a9eb172552348a9a49180694790b33a1097f546456d041b6e82e4d7716ddb721"}}

and

	docker save a9eb17255234 | tar t

Before:
	[...]
	a9eb17255234/
	a9eb17255234/VERSION
	a9eb17255234/json
	a9eb17255234/layer.tar
	# Note the truncated layer name

Now:
	[...]
	a9eb172552348a9a49180694790b33a1097f546456d041b6e82e4d7716ddb721/
	a9eb172552348a9a49180694790b33a1097f546456d041b6e82e4d7716ddb721/VERSION
	a9eb172552348a9a49180694790b33a1097f546456d041b6e82e4d7716ddb721/json
	a9eb172552348a9a49180694790b33a1097f546456d041b6e82e4d7716ddb721/layer.tar
	# There is no 'repositories' file, because there is no named repo

Docker-DCO-1.1-Signed-off-by: Vincent Batts <vbatts@redhat.com> (github: vbatts)
add jclouds-docker client reference

Docker-DCO-1.1-Signed-off-by: Andrea Turli <andrea.turli@gmail.com> (github: andreaturli)

Docker-DCO-1.1-Signed-off-by: Andrea Turli <andrea.turli@gmail.com> (github: )
Update running_riak_service.md
Update Makefile to default BINDDIR to nothing if DOCKER_HOST is set

If "DOCKER_HOST" is set, we can usually assume the user is connecting to a remote Docker and thus not bind mount anything by default (meaning the Makefile will more often DWIM for our users).

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
docker save: more integration tests

Docker-DCO-1.1-Signed-off-by: Vincent Batts <vbatts@redhat.com> (github: vbatts)
We haven't required lxc and aufs for years now...

Well, maybe not years, but internet years...

Docker-DCO-1.1-Signed-off-by: Timothy Hobbs <timothyhobbs@seznam.cz> (github: timthelion)
Convert TestGetImagesJSON into several unit tests

Docker-DCO-1.1-Signed-off-by: Guilherme Salgado <gsalgado@gmail.com> (github: gsalgado)
Merge pull request #6829 from unclejack/update_archive_tar

update vendored archive/tar to lower the number of memory allocations
Merge pull request #6813 from gsalgado/convert-testgetimagesjson

Convert TestGetImagesJSON into several unit tests
Merge pull request #6857 from vbatts/vbatts-fix_save_repositories

docker save: fix the 'repositories' file
Merge pull request #6720 from fabiofalci/relax_dns_search

Relax dns search to accept empty domain
Merge pull request #6886 from tianon/no-binddir-if-docker_host

Update Makefile to default BINDDIR to nothing if DOCKER_HOST is set
Merge pull request #6870 from andreaturli/doc/jclouds-client

add jclouds-docker client reference
Merge pull request #6871 from prosto-chewey/patch-1

Update running_riak_service.md
Merge pull request #6858 from timthelion/patch-6

We haven't required lxc and aufs for years now...
Merge pull request #6849 from leeplay/patch-1

Update README.md