Patch Number of Favorites

Adds a log handler to the hentai module and implements a fallback mechanism to the num_favorites property of Hentai objects for recently uploaded doujins whose values (as they're returned by the API) equals 0 for a few weeks before they retain their actual number of favorites. This version also deprecates setup.cfg and made a few additional changes to the project structure, none of which should have any effect on users of this library.