Data source whose backing is a JSON-like service, in which
retreiving the resource specified by URL with the additional parameter
callback. The resource retreived is executable JavaScript that
makes a call to the named function with a JavaScript object literal
as the only parameter.
Example URI could be:
http://www.google.com/data/search?q=monkey&callback=mycb
which might return the JS:
mycb({searchresults:
[{uri: 'http://www.monkey.com', title: 'Site About Monkeys'}]});
TODO(user): Evaluate using goog.net.Jsonp here.
A URI of an empty string will mean that no request is made
and the data source will be a data source with no child nodes