Suggest replacements of SHA-1 intermediate certs with known SHA-2 certs

So as more information becomes available from issue#24 we can add more certs to the `fingerprints.json` file.

Essentially think this works but @konklone should probably go over the code. Also I've added a simple check to only run the `.sha2URL` method when we aren't looking at a root certificate. Could probably make that check step even better as we wouldn't need to run the method on the site's actual certificate.
Would this perhaps be the best place to send people? https://knowledge.verisign.com/support/ssl-certificates-support/index?page=content&id=AR657&actp=LIST&viewlocale=en_US

It has links for all the different intermediate CA certifcates.