Is it possible to structure
/sites/all/modules/civicrm/extern/rest.php?entity=Activity&action=create&json={"sequential":1,"activity_date_time":"2015-09-01","id":2,"subject":"test","target_id":"1529697","status_id":2}&api_key=X&key=Y
without the JSON section? I'm integrating with Survey Gizmo and it assumes all REST calls will be in format ?variable=value&variable=value etc..