Adds steps of scraper before data is actually used

This is just for parts of the scraping pipeline.

One part simply pulls the data down

Another part transforms the raw data into something that I think is useful.

Details:

1. From what I can see, **capsule_image** is the logo that doesn't change. **header_image** changes I'm pretty sure depending on whatever Steams marketing and design team decides I guess.
2. Instead of having to remember what app id we were working with we can just scrape it out of the page
3. We collect all the categories for a game, this means we can add more features later if we want. It also means that if a game supports single player and multi-player we'll know (though for our purpose this really doesn't matter).

Please review @carsonb @davefp