Rubygems integration?

[phillmv]

This ticket reflects an ongoing discussion we've been having with the Rubygems peeps, but:

In the advent of a "yank gem for security reasons" feature being added to rubygems, it'd be great if we could capture such information via webhook or other mechanism and add it to the advisory-db.

[phillmv]

(This is actually what motivated switching from a simple jekyll site to a more complicated-to-host rails app)