Web site needs updating with new drafts/meta-schema

[handrews]

@stefk noted in json-schema/json-schema#198 that the web site still shows the Draft 04 specifications and meta-schemas. @awwright I imagine you're already on this but filing as @stefk wanted to still track this after closing the issue at the old repo.

[Relequestual]

I'd like to close this in favour of #51

[awwright]

Yeah, it appears #42 covered this

[handrews]

As noted above, this is covered elsewhere.