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)
docker save: Do not save to a terminal.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
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)
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)
DOCKER_VERSION and docker-version havn't been implemented.

So far, it looks like the declarations are not used, and so its safer not to
confuse people into thinking they do something.

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@docker.com> (github: SvenDowideit)
Fixes #8690

Docker-DCO-1.1-Signed-off-by: Jessica Frazelle <jess@docker.com> (github: jfrazelle)
Merge pull request #8692 from jfrazelle/8690-latest-tag-problem

Fix problem where building Dockerfile `FROM name:latest`
Merge pull request #8672 from estesp/CmdRun-fix-typos-comments

Clean up comment sections and fix typos in CmdRun
Correct url from github.com/dotcloud/docker{,-py}
to github.com/docker/docker{,-py}

Signed-off-by: Torstein Husebø <torstein@huseboe.net>
Add MemInfo to the system pkg.

MemInfo provides a simple API to get memory information from the
system.

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>
TestRunRedirectStdout kept failing with timed out.

Docker-DCO-1.1-Signed-off-by: Jessica Frazelle <jess@docker.com> (github: jfrazelle)
Merge pull request #8708 from torstehu/fix-url

Correct url from github.com/dotcloud/docker{,-py}
Merge pull request #8673 from SvenDowideit/whats-docker-version

DOCKER_VERSION and docker-version havn't been implemented.
Merge pull request #8718 from jfrazelle/run-redirect-test-fix

TestRunRedirectStdout kept failing with timed out.
Rewrite ENTRYPOINT documentation covering all the combinations with examples.

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@docker.com> (github: SvenDowideit)
save start error into State.Error

when a container failed to start, saves the error message into State.Error so
that it can be retrieved when calling `docker inspect` instead of having to
look at the log

Docker-DCO-1.1-Signed-off-by: Daniel, Dao Quang Minh <dqminh89@gmail.com> (github: dqminh)
Port number 49153(BeginPortRange) would be returned twice, causing duplication and potential errors.

If we first request port 49153 (BeginPortRange) explicitly, and later some time request the next free port (of same ip/proto) by calling RequestPort() with port number 0, we will again get 49153 returned, even if it's currently in use. Because findPort() blindly retured BeginPortRange the first run, without checking if it has already been taken.

Signed-off-by: shuai-z <zs.broccoli@gmail.com>
added test, gofmtd

Signed-off-by: shuai-z <zs.broccoli@gmail.com>
Merge pull request #8550 from aluzzardi/f-meminfo

system: Add MemInfo utility.