Add centos/redhat 7 support

The version scheme between RHEL7 and CentOS7 differ. This enburdens
us to make quarterly changes to keep this cookbook functioning if
we are explicit with versions.
By making systemd 'default' for rhel family, we can take advantage
of the regular version scheme of 6.x to correctly identify them
as 'sysv'. So, 'systemd' is now the default for this family.
Add el6.6 to attributes
Incorproate updates to sysv from upstream
Explicitly set key and keyserver, so we don't make a request to get.docker.io on every chef run.
Update CHANGELOG with previous commit details
PR#220 - Create graph directory if it is specified
Merge PR#219 - Explicity set Upstart provider

Explicity set the upstart provider for cgroups.
Apply a few remaining rspec 3.0 fixes

Cherry-picked from PR#223 from jperville
Replace ChefSpec::Runner with ChefSpec::SoloRunner

Addressed the depreceation warning.
Replace define_runner_method with define_matcher

Addressed deprecation warning from ChefSpec
Update stub_command to search for "go1.2"

Addresses error that was causing some tests to fail.
Constrain serverspec version in kitchen tests
Merge PR#224 - Fix runit container template

The current template tries to run two successive lines with exec. But since exec causes the current process to be replaced, the second line is never run. This causes runit to always report that the container service is down and to continually try to restart it.

Just remove the first exec to fix.
Update Berksfile to pull from supermarket

Update the Berksfile to reference 'supermarket.getchef.com' instead of 'api.berkshelf.com'
Add 1.0 breaking change notice

In 1.0, we will a big breaking change. I am adding info about that breaking change to the README and printing it in the logs when docker_container is used.
Fix LXC check on Fedora when using binary install
Pull in upstream systemd service file changes
LXC fixes

1) Condense LXC package installation instructions
2) Implement workaround to upgrade libcgmanager on Ubuntu 14.04 due to lxc/lxc#247.
Add default value for dependency_packages

Add a default value of an empty array to the dependency_packages array so we don't get nil errors.
Fixes to test matrix