Docker support

Here's a `Dockerfile` for building a [Docker](https://www.docker.io/) container image that can easily be used to run glastopf.

Furthermore if you decide to publish the built docker container image on the [Docker index](https://index.docker.io/), then running glastopf will be just a one-liner. No more how-to-install-dependencies for new comers.

See [the one](https://index.docker.io/u/tomdesinto/glastopf/) I've published.

If you don't know Docker, it can easily be installed on Ubuntu 14.04 with `sudo apt-get install docker.io`. Complete install instructions are [here](http://docs.docker.io/installation/ubuntulinux/#ubuntu-trusty-1404-lts-64-bit).

Also more and more hosting companies are offering images with a Linux system having Docker pre-installed and ready to go ([Amazon EC2](http://docs.docker.io/installation/amazon/), [DigitalOcean](https://www.digitalocean.com/community/articles/how-to-use-the-digitalocean-docker-application))