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)
Adding self to various maintainers files.

Docker-DCO-1.1-Signed-off-by: Jessica Frazelle <jess@docker.com> (github: jfrazelle)
pkg/version: lint and add comments
docker save: Do not save to a terminal.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
pkg/truncindex: lint and add comments

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
pkg/units: lint

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
pkg/timeutils: lint and add comments

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

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
pkg/graphdb: some linting

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
Fix the bug of tag a existed tag name of a repository.

Signed-off-by: Lei Jitang <leijitang@huawei.com>
Migrate container GET API tests from integration to integration-cli

An initial start to migration of the API tests from integration to
the integration-cli model.

Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com>
(github: estesp)
Don't write pull output to stdout on container creating

Fixes #8632

Signed-off-by: Alexandr Morozov <lk4d4@docker.com>
install.sh: Fix for Amazon's Linux AMI

Use /etc/os-release to determine distro

Contents of /etc/os-release on Amazon Linux AMI 2014.09:
NAME="Amazon Linux AMI"
VERSION="2014.09"
ID="amzn"
ID_LIKE="rhel fedora"
VERSION_ID="2014.09"
PRETTY_NAME="Amazon Linux AMI 2014.09"
ANSI_COLOR="0;33"
CPE_NAME="cpe:/o:amazon:linux:2014.09:ga"
HOME_URL="http://aws.amazon.com/amazon-linux-ami/"

Signed-off-by: Amit Bakshi <ambakshi@gmail.com>
Signed-off-by: Jessica Frazelle <jess@docker.com>
check ID in os-release instead

Docker-DCO-1.1-Signed-off-by: Jessica Frazelle <jess@docker.com> (github: jfrazelle)
Return container exit code with start -a/-i
Addresses #8555

Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com>
Clean up comment sections and fix typos in CmdRun

Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com> (github: estesp)
Add docker tag tests.

Signed-off-by: Lei Jitang <leijitang@huawei.com>
small typo
zsh: update zsh completion for docker command

zsh completion is updated with the content of
felixr/docker-zsh-completion.

The major change since the last merge is the addition of
exec/create (but they were already present in the docker repository) as
well as pause/unpause/logout/events and the use of short/long options
when they are available. Some missing options were also added.

12f00abd7178 Add completion for `exec'
4e2faa075f9a Merge `run' and `create' commands.
34134de077de Add missing long/short options for most commands.
d09f62339ab5 Add completion for `pause' and `unpause'
e4754c3b3b9d Add completion for `logout'
e0935eb3d5d2 Add completion for `events'
dae353cb9afb Add completion for `create`

Docker-DCO-1.1-Signed-off-by: Vincent Bernat <vincent@bernat.im> (github: vincentbernat)
On Red Hat Registry Servers we return 404 on certification errors.

We do this to prevent leakage of information, we don't want people
to be able to probe for existing content.

According to RFC 2616, "This status code (404) is commonly used when the server does not
wish to reveal exactly why the request has been refused, or when no other response i
is applicable."

https://www.ietf.org/rfc/rfc2616.txt

10.4.4 403 Forbidden

   The server understood the request, but is refusing to fulfill it.
   Authorization will not help and the request SHOULD NOT be repeated.
   If the request method was not HEAD and the server wishes to make
   public why the request has not been fulfilled, it SHOULD describe the
   reason for the refusal in the entity.  If the server does not wish to
   make this information available to the client, the status code 404
   (Not Found) can be used instead.

10.4.5 404 Not Found

   The server has not found anything matching the Request-URI. No
   indication is given of whether the condition is temporary or
   permanent. The 410 (Gone) status code SHOULD be used if the server
   knows, through some internally configurable mechanism, that an old
   resource is permanently unavailable and has no forwarding address.
   This status code is commonly used when the server does not wish to
   reveal exactly why the request has been refused, or when no other
   response is applicable.

When docker is running through its certificates, it should continue
trying with a new certificate even if it gets back a 404 error code.

Docker-DCO-1.1-Signed-off-by: Dan Walsh <dwalsh@redhat.com> (github: rhatdan)