Basic acceptance test which starts up a local cluster and verifies all nodes join via querying the gossip network.

Summary:
Combined the init/start commands so that "cockroach init" actually starts
the server after bootstrapping. This makes deployment simpler.

Exposed json contents of gossip network via _status/gossip endpoint.

Updated README file with new deployment steps: building docker and running
a local cluster.

Added a script for deploying a local cluster using docker containerization.

Rewrote dockerfile.

I originally tried to do everything through the vagrant docker provider
but simply couldn't get it to work. After hours of frustrated effort,
I settled on this approach which just requires local installation of
docker. For MacOS and Windows, this is simplest via the boot2docker
installation, which runs VirtualBox and Tiny Core Linux for a minimal
linux VM.

Test Plan: make test / make acceptance

Reviewers: strangemonad, Tobias, bdarnell, andybons

Reviewed By: bdarnell

Subscribers: team

Differential Revision: http://phabricator.cockroachdb.org/D162