Normalized weekly epicurve per geographical area

[cathinkaw]

This is an extension of: https://github.com/IFRCGo/cbs/issues/858 and is probably only linked to how the data is fed into graph:

The graph should show:

(number of reported cases) / (estimation population) * 10000 (i.e. number of reported cases per 10.000 population).

The creation of the data set can either be done in the backend or the frontend.