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.
Well that's not a cery [cool URL](http://www.w3.org/Provider/Style/URI)!