Updated ThreeSection Subdomain parser to look for an IP Address

Currently AR looks for multiple "."s to determine if the request is to a sub-domain or not. But if you navigate to the site via an IP it incorrectly identifies the sub-domain. i.e. you go to your site at http://127.0.0.1:81/ the sub-domain would be "127.0".

Updated the ThreeSection Subdomain parser to test the host for being an IP address and returns null if it is. Tests have been added for IP and IP w/Port.