Change: configuration, vagrant, &documentation.

Change riak backend inside container to leveldb.
Enable search in riak.
Add Vagrantfile with docker provisioner to make testing easier.
Add documentation to README.md about the Vagrantfile.
Add documentation to README.md about running the container with port mapping.
Add documentation to README.md about using search.
Change: refactor dockerfile.

Use https://github.com/hectcastro/docker-riak as a base.
Change: ssh instructions in readme.
Merge pull request #1 from nisaacson/config_with_vagrant

Config with vagrant