Added support for JsonView output, used in Zend Framework 2.x

- Added support for JsonView output, used in Zend Framework 2.x
 + There is new option in the config: 'root'
 + Below sample JSON output:

```
    {
      "events" : [{
        "id" : 14,
        "title" : "New Year",
        "start" : "2013-01-01",
        "end" : "2013-01-01",
        "allDay" : true
      }, {
        "id" : 15,
        "title" : "Epiphany",
        "start" : "2013-01-06",
        "end" : "2013-01-06",
        "allDay" : true
      }, {
        "id" : 16,
        "title" : "Easter Sunday",
        "start" : "2013-03-31",
        "end" : "2013-03-31",
        "allDay" : true
      }, {
        "id" : 17,
        "title" : "Easter Monday",
        "start" : "2013-04-01",
        "end" : "2013-04-01",
        "allDay" : true
      }],
      "success" : true
    }
```