Create prediction engine

[YgLK]

Create neural network (NN) which will be used for air quality data prediction.

• Create NN model used for air quality predictions
• After each prediction, store predicted data in the Predicted Measurement db table
• Test and validate NN performance. Tests can be performed and visualized in the Jupyter Notebook and put in the backend/tests/engine/<notebook_nam>.ipynb

Data retrieved from the database might not be ready right away to be learnt on.

• Create essential methods for data preparation in the data_processing module