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)
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)
small typo
Clean volume paths
Fixes #8659

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
Link to run reference from cli doc

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

Signed-off-by: Zach Borboa <zachborboa@gmail.com>
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)
Merge pull request #8665 from cpuguy83/8659_clean_paths_for_volumes

Clean volume paths
Merge pull request #8423 from unclejack/lint_changes

lint changes part 1