Bug fix
- Removed support for Python 2
- Changes to creating DER model instance using "DERModel" class.
- Removed the need to specify "modelType" when creating a model instance. The model type is specified in the config file now.
- "derID" is now a required argument.
- "powerRating" and "VrmsRating" can only be supplied through the config file now.
- Minor refactoring and code cleanup.
- Added Dockerfile for using high-performance Julia ODE solvers library - Acknowledgement to Abel Siqueira (Netherlands eScience Center)