feat(contrib/coreos): add etcd debug unit

This adds an optional service to aid in debugging etcd issues.
Note that it's only enabled in the cloud-config file, not started.
This enables users to `sudo systemctl start debug-etcd` on a machine
before performing tasks which may strain etcd (such as heavy IO),
and then watch the service's journal to see how things like heartbeat
intervals change.
docs(troubleshooting_deis): document debug-etcd service
fix(slugbuilder): allow users to cat slugfile

partially reverts deis/slugbuilder@b872515
style(builder): convert tabs to spaces
feat(pkg): add pkg time

This package is used to control how we utilize the time package across
the Deis Platform, including application logs, component logs, API
datetime structures, etc.
chore(slugbuilder): bump heroku buildpacks
docs(using_buildpacks): add sidenote on Scala buildpack

Play v2.0 apps and above use the Scala buildpack, which requires
a minimum of 512MB for to execute sbt, which invokes the JRE.
Merge pull request #2769 from bacongobbler/bump-buildpacks

chore(slugbuilder): bump heroku buildpacks
docs(releases): update with major/minor and patch procedures
feat(contrib/ec2): use separate volume for /var/lib/docker

We've seen fewer performance issues when machines use a separate
volume for /var/lib/docker. This commit changes the AWS provision
script to automatically prepare and mount a separate volume for
Docker.

We have to touch `/etc/docker-volume-formatted` because the
user-data is applied on every reboot, and we don't want
the Docker graph getting destroyed.

Note that we use the device name `/dev/xvdf` irrespective
of the instance virtualization type (PV or HVM). This seems to be
the way the kernel maps the block device, and isn't necessarily
unusual - see http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ebs-using-volumes.html

Amazon documentation suggests using the letter 'f' as the first name
of a non-root EBS-backed device: http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/block-device-mapping-concepts.html

I manually tested this on both PV and HVM instances and had no issues.
There is no change in UX other than the new requirement of installing
the PyYAML Python library.
Merge pull request #2768 from bacongobbler/refactor-time

feat(pkg): add pkg time
ref(controller): remove redis cache library and settings

CACHE_URL and the python Redis library were not actually being
used by the controller.
chore(contrib/rackspace): bump to CoreOS 494.5.0
Merge pull request #2808 from carmstrong/rackspace-494.5.0

chore(contrib/rackspace): bump to CoreOS 494.5.0
Merge pull request #2794 from bacongobbler/2740-slugbuilder-to-stdout

fix(builder): allow users to cat slugfile
chore(controller): update South to 1.0.2 bugfix release
chore(cache): update Redis to 2.8.19

See https://raw.githubusercontent.com/antirez/redis/2.8/00-RELEASENOTES
fix(client): encode unicode properly for apps:run
Merge pull request #2779 from carmstrong/feat-debug_etcd

feat(contrib/coreos): add etcd debug unit
Merge pull request #2800 from mboersma/update-rel-docs

docs(releases): update with major/minor and patch procedures