Added the option to output a prices json file in main.py under --prices-with-promos, where the prices are updated by the latest promotions (under the 'final_price' key, where 'price' represents the price before promotions).
Fixed small bug of BinaWebCleint by checking that filename does not contain 'null'.
Changed Hierarchy of chains such that it includes the webclients.
Added the date to the output filenames to start storing the data over time.
Black formatting (according to pip 8 guidelines).
Changed the chains_dict in main to a constant one.
