PublicDNS: Reorder the list of DNS providers.

We're trying to offer alternatives to Google, so I think it should not be on the first one. Tell me what you guys think!
PublicDNS: Fixed broken link (Norton)
Public DNS: Sorted alphabetically.
Merge pull request #372 from duckduckgo/jag/dns

PublicDNS: Reorder the list of DNS providers.