Support jsonp in externals
Support jsonp in externals

Allow ?callback= for any external that returns json (i.e,
uses "json":{} instead of "data":"data".

BugzID: 12748

fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb