Dev/data prep

[marcelo-borghetti]

Main changes:

• SRC/: folder with data_downloader.py, normalization_builder.py, and timeseries_builder. These files contain the main source code. All other files in this folder and other folders are either supporting code or are using these files.
• NOTEBOOKS/: example notebooks showing how to instantiate the classes on the SRC folder. It is not a priority to review this, but it is good to take a look.
• SCRIPTS/: example scripts showing how to instantiate the classes on the SRC folder. It is not a priority to review this, but it is good to take a look. Suggestion: you can start the review with these files if you want to follow a flow of execution.
• DATA/: it contains lightweight files. I did not commit any large-size file, since this can crash the repository.
• MODELS/: it contains lightweight models. I did not commit any large-size file, since this can crash the repository.