update: Added a basic Dockerfile

* Added a basic Dockerfile with nodejs and mongodb to start to use
  tournamenter in a way it deserves.

Signed-off-by: mr.Shu <mr@shu.io>

----------

This is a very first and very basic version of a Dockerfile that will in the end power `tournamenter`.

To get this, first of all you need to install docker (http://docs.docker.com/installation/mac/). Then you need to pull my build by running

```
docker pull mrshu/tournamenter
```

It's going to install a LOT of data (like around 800MB) but afterwards you can run

```
sudo docker run -p 12345:1337 -a stdin -a stdout -i -t mrshu/tournamenter 
```

Which will start tournamenter, open port 12345 on your machine and route the "internal" tournamenter's port (1337) into it. That way, tournamenter should be now available at http://127.0.0.1:12345/ on your machine.

@ivanseidel Do let me know if there are any problems with this -- would like to get them figured out.