Added the Dockerfile

This dockerfile represents how the image binnisb/concoct_0.2.1 on https://index.docker.io/ was created. It is here to only for us to be able to update the image on https://index.docker.io/ easily. No user that wants to run concoct needs to use this file. They should pull the image from https://index.docker.io/.

We can now update the README to explain how one can clone the image from https://index.docker.io/, log in  to the docker and run concoct

The simplest command to download the image and log into the shell, after setting up docker is:
<code>
sudo docker run -v /my/host/shared/directory:/my/docker/location -i -t binnisb/concoct_0.2.1 /bin/bash
</code>

This leaves you in a shell that has all dependencies for concoct installed and maps the folder /my/host/shared/directory from the host computer to the folder /my/docker/location in the docker image. So if you copy your data to /my/host/shared/directory it will be available in the docker folder.

The next command you should run in the docker shell is then:
<code>
cd /opt/CONCOCT
nosetests
</code>
And make sure it executes without errors

To update the image you make changes to this file, build it with the tag you want for it and then push it to the repository:
<code>
sudo docker build -t binnisb/concoct_0.2.1 - < Dockerfile
sudo docker push binnisb/concoct_0.2.1
</code>