Integrate tests

[mathisloevenich]

To quote @nhjjreuter :

I recommend getting rid of the input and getpass parts. Tests should be automated. 
Instead, use either an .env file (and then import os; os.environ.get('eaton_ups_username')), 
or a .config.json/yaml file that you likewise draw your data from. Then just put the file with the password data in .gitignore