Added a Dockerfile to the project

First run `docker build .` to build the camlistored image. Note the last
container ID for later. If the build fails make sure your machine has 1G+ of
memory.

Then `docker run $CONTAINER_ID`. You can use `docker ps` to find the wher
docker has mapped the 3179 port locally.

TODO:
 * Add persistance.
 * Maybe provide a different config than the default ?
 * Only build camlistored if this is what we're going to use.