add --releasever=/ to mkimage-yum.sh

I didn't realize the commit required a Docker-DCO so it failed the travis-ci build. So I removed the commit from my forked repo. Now it looks like there is a pull request with no commit. So here it is again:

Needed to add '--releasever=/' flag to run yum groupinstall on Centos7 (didn't try on anything else). This snippet from yum man page explains why:

```
Note: You may also want to use the option --releasever=/ when creating the installroot as otherwise the $releasever value is taken from the rpmdb within the installroot (and thus.  will  be  empty,  before  creation).
```

Docker-DCO-1.1-Signed-off-by: Matt Schurenko <matt.schurenko@gmail.com> (github: mschurenko)
More ipallocator refactoring

Now x1.5 faster

Signed-off-by: Alexandr Morozov <lk4d4math@gmail.com>
Implement allocating IPs from CIDR within bridge network

Fixes #4986

Signed-off-by: Alexandr Morozov <lk4d4math@gmail.com>
Adding first draft of Official Repo Guidelines

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: fredlf)
use tune2fs to disable ext4 mount counts and mount intervals
Signed-off-by: Marc Tamsky <mtamsky@gmail.com> (github: tamsky)
Fix gh#7747 - filter bare newline output and log client pull to stdout

Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com> (github: estesp)
Fix duplicate iptables rules

If iptables version is < 1.4.11, try to delete the rule vs. checking if it exists. Fixes #6831.

Docker-DCO-1.1-Signed-off-by: Jessica Frazelle <jfrazelle@users.noreply.github.com> (github: jfrazelle)
Revisions based on feedback.

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: fredlf)
Format and typo fixes

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: fredlf)
Print consistent help with options and commands

These commands now all output the same thing:

 - docker
 - docker help
 - docker --help
 - docker -h

Signed-off-by: Ben Firshman <ben@firshman.co.uk>
Add instructions on how to get help on commands

Signed-off-by: Ben Firshman <ben@firshman.co.uk>
More format fixes.

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: fredlf)
More format wrestling.

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: fredlf)
Consolidate documentation for -H option

Signed-off-by: Ben Firshman <ben@firshman.co.uk>
Update libcontainer to 84ad9386a0240acb7475429a835

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
Add daemon flag to specify public registry mirrors

Adds support for a --registry-mirror=scheme://<host>[:port]
daemon flag. The flag may be present multiple times. If
provided, mirrors are prepended to the list of endpoints used
for image pull. Note that only mirrors of the public
index.docker.io registry are supported, and image/tag resolution
is still performed via the official index.

Docker-DCO-1.1-Signed-off-by: Tim Smith <timbot@google.com> (github: timbot)
Deallocate port before trying to delete iptables chain

Fixes #7954
Signed-off-by: Alexandr Morozov <lk4d4math@gmail.com>
Merge pull request #7955 from LK4D4/ignore_delete_err_on_unmap_#7954

Deallocate port before trying to delete iptables chain
Fix link for configuring automated builds
TarSum: versioning

This introduces Versions for TarSum checksums.
Fixes: https://github.com/docker/docker/issues/7526

It preserves current functionality and abstracts the interface for
future flexibility of hashing algorithms. As a POC, the VersionDev
Tarsum does not include the mtime in the checksum calculation, and would
solve https://github.com/docker/docker/issues/7387 though this is not a
settled Version is subject to change until a version number is assigned.

Signed-off-by: Vincent Batts <vbatts@redhat.com>