Scraper temporary fixes

[RajcaS]

This PR introduces:

• improved mapping based on https://github.com/JoMingyu/google-play-scraper (unfortunately, not all mappings can be easily adapted from that repo) - I've verified that scraper and it works (fixed mapping was introduced 3 days ago)
• commented-out functionalities that don't work right now (they may be reverted if needed)

As discussed offline, I'm not going to merge this PR now. It introduces many changes which can break the user's code. However, according to my experience with the main version for today, the whole bunch of functionalities is broken due to changes in responses from Google Play. This PR fixes most of the app() response fields, but there is no plan, for now, to deal with other issues.