RawPixel Improvements

[zackkrida]

I suspect our RawPixel DAG doesn't work. I haven't tested it yet, but the endpoint in our docs:

• https://api.rawpixel.com/api/v1/search?freecc0=1&html=0

doesn't appear to work. Meanwhile, the site's internal api when you make a search on the site looks like this:

• https://www.rawpixel.com/api/v1/search?keys=kitten&page=1&sort=new

Each result has an isCC0 boolean property we can use to detect CC0 compatibility, instead of the previous query param.

These images look really good, and combined with #744 this would also really improve the result quality of some common 'stock' search terms.