OSB-34: Setup of the preliminary implementation of the celery infrastructure, integration with the already existring django infrastructure and modification of the models to include and serve the RTSM plots

OSB-32: added additional filter field in the api requests to select the error types and url generation for the RTSM plots

OSB-28: add ordering by date and change in the summary parameters to include a lookback time instead of a datetime

OSB-28: Removed the RTSMObservationSummary model and modified the RTSMObservation to include a summary of the RTSM