Configuration files into `.ini` files

[ludgerpaehler]

Restructuring our environment definitions s.t. we have default configuration files loaded with the configuration manager, i.e. we can then load them with the configuration manager from Python.

Closes #161

Will enable us down the line to better template default environment configurations.

[ludgerpaehler]

I.e. for configuration file documentation:

https://docs.python.org/3/library/configparser.html