Add basic structure and code formatting

Create a basic structure for a Python project. You can guide yourself with our example project betty. A basic structure consists in:

• A suitable .gitignore file
• A basic setup.py
• A directory for the code with the name of the package, including a first python file file
• A directory for the tests, including a first test file with a dummy test
• A Makefile to add code checking

/cc @ds @shinde