Unify covid-cases dataset and cluster based on this single-dataset

[anaPerezGhiglia]

Define clusters based on a single dataset to ensure all regions are on the same scale (and only in one)

• Try using Jenks with 10 bins - check if the US states are not all in the same cluster
• If not, split the dataset in two, and run jenks on each half with four bins. Use the max-cases-state as the splitting point

Expose the ranges limits in the api