Add support for Rubygems

[dcramer]

https://rubygems.org/pages/data

[stayallive]

It looks like there is only total downloads and downloads per version.

Don't know how much it's updated but we might need to check each package everyday and generate our own downloads delta to store the daily downloads and use that to generate historical data.

If anyone has ideas or knows where we could find better or more easy to use data about the downloads I'm all ears!

[Marhc]

BestGems has a Daily Downloads Ranking

[stayallive]

From the looks of it they scrape the data from the rubygems site.

We can do that as well pretty easily (already doing that for PyPI and Hex) but there is no telling when the counter is updating on that page so we would be getting some pretty inconsistent data unless we scrape on the exact same moment each day (and even then).

But it might be worth a shot... better than nothing :)