code: def provider_from_url(self, url):
          
          domain = get_domain(url)
          site_tuples = self.get_cleaned_sites().values()
          for domain_re, name, normalized_domain in site_tuples:
              if re.match(domain_re, domain):
                  return normalized_domain, name
          site = Site.objects.get_current()
          return site.domain, site.name
docs: Given a URL for any of our sites, try and match it to one, returning
          the domain & name of the match.  If no match is found, return current.
          
          Returns a tuple of domain, site name -- used to determine 'provider'