Image change, add readme content and add a command for convenience.

- Cut out unnecessary white space from the image used in the readme.
- Add a secondary image as a replacement for the first if it is deemed better.
- Add content to the readme file. Hopefully the install instructions are correct.
- Add command to the build script that renames the `settings.example.py` file to `settings.py`.
You don't need a system pip. And virtualenv is packaged in debian. `python-virtualenv`