title: Laravel 5 return datetime with timezone
body: <p>I am building an API and I would like to return all my timestamps like created_at, deleted_at, ... and so on as complex objects including the actual datetime, but also the timezone. 
  I am already using {Carbon/Carbon}in my Controller. I defined my date field in the model as well.
  When I access the date fields in my controller, I actually get Carbon objects. But when I return my result set as JSON, I only see the datetime string. Not the timezone. </p>
  
  <p><strong>Current JSON</strong></p>
  
  <pre><code>{
      "id": 4,
      "username": "purusScarlett93",
      "firstname": null,
      "lastname": null,
      "language_id": 1,
      "pic": null,
      "email": null,
      "authtoken": "f54e17b2ffc7203afe345d947f0bf8ceab954ac4f08cc19990fc41d53fe4eef8",
      "authdate": "2015-05-27 12:31:13",
      "activation_code": null,
      "active": 0,
      "devices": [],
      "sports": []
  }
  </code></pre>
  
  <p><strong>My wish :)</strong> </p>
  
  <pre><code>{
    "id": 4,
    "username": "purusScarlett93",
    "firstname": null,
    "language_id": 1,
    "pic": null,
    "email": null,
     "authtoken":"f54e17b2ffc7203afe41d53fe4eef8",
     "authdate": [
       {
         "datetime": "2015-05-27 12:31:13",
         "timezone": "UTC+2"
       }
     ],
     "activation_code": null,
     "active": 0
   }
  </code></pre>
  
  <p>Any idea what I am missing here?</p>