backend hanwatts prediction model web interface

Merge pull request #2 in UPRFIR/backend-hanwatts-prediction-model-web-interface from UPRFIR-135-Weather-data-ophalen to development

* commit '76ad3d5fbb24d02d52148c232910f705c62e85c9':
  betere domain class
  kleine name chabngw
  more clean code fixes
  cleaner code
  weather fetch
  update endpoints in readme
  insert and get weather