DS.RESTAdapter#ajax()

Takes a URL, an HTTP method and a hash of data, and makes an HTTP request.

When the server responds with a payload, Ember Data will call into extractSingle or extractArray (depending on whether the original query was for one record or many records).

By default, ajax method has the following behavior:

• It sets the response dataType to "json"
• If the HTTP method is not "GET", it sets the Content-Type to be application/json; charset=utf-8
• If the HTTP method is not "GET", it stringifies the data passed in. The data is the serialized record in the case of a save.
• Registers success and failure handlers.