reintroduce allow_functionality subscription

 * contains rules needed for the top100 websites to work as expected
 * top100 list from http://www.alexa.com/topsites
 * these rules are not suitable for allow_sameorg (cross-site requests from/to different organizations)
 * add back allow_functionality entry in official.json subscriptions list
 * fixes RequestPolicyContinued#9
So just to clarify, this file does not also allow access from bitbucket.org to bitbucket-assetroot.s3.amazonaws.com because amazon aws is only used to source some logo images for bitbucket? 

Just trying to clarify the difference between this and imgur.com for stack exchange sites above.