Sketch of implementation.
A NamespacedDockerClient that isn't actually namespaced yet, but is a
docker client.
Add a container_name attribute to Unit.

This allows some improvements to tests since we now know where to find
the container.
Delete some unused imports.
NamespacedDockerClient now works.
Skip tests if Docker is unavailable.
Fix some other tests that used Unit().
Merge pull request #817 from ClusterHQ/noop-scheduler-235

Force the use of noop ioscheduler in tutorial vagrant vms

Authors: @wallrj, @ryao
Reviewer: @exarkun

Fixes #235
Bumped version numbers
Updated NEWS
Lint fix.
Update documentation to note we no longer have a container-data helper container.
Merge pull request #849 from ClusterHQ/release/flocker-0.2.1

Release Flocker-0.2.1

Author: @wallrj
Reviewer: @adamtheturtle 

Fixes #847
Address review comment: Include test name in namespace.
Merge pull request #841 from ClusterHQ/dockerclient-namespacing-772

Dockerclient namespacing.

Fixes #772.
Merge remote-tracking branch 'refs/remotes/origin/master' into better-volume-support-in-dockerclient-234

Conflicts:
	flocker/node/_docker.py