title: Rails rabl json format
body: <p>I'm displaying data from my db in json format using rabl to parse it for android...
  My json looks like so:</p>
  
  <pre><code>[
     {
        "bank":{
           "central_office_address":"ololo",
           "license":"12312312",
           "location_id":3,
           "name":"Pbank",
           "tax_number":"12312312",
           "year_of_foundation":1987
        }
     },
     {
        "bank":{
           "central_office_address":"sdfsdf sdf",
           "license":"321312",
           "location_id":3,
           "name":"Bbank",
           "tax_number":"321321",
           "year_of_foundation":1999
        }
     }
  ]
  </code></pre>
  
  <p>I need my json in a format like:</p>
  
  <pre><code>{
      "contacts": [
          {
                  "id": "c200",
                  "name": "Ravi Tamada",
                  "email": "ravi@gmail.com",
                  "address": "xx-xx-xxxx,x - street, x - country",
                  "gender" : "male",
                  "phone": {
                      "mobile": "+91 0000000000",
                      "home": "00 000000",
                      "office": "00 000000"
                  }
          },
          {
                  "id": "c201",
                  "name": "Johnny Depp",
                  "email": "johnny_depp@gmail.com",
                  "address": "xx-xx-xxxx,x - street, x - country",
                  "gender" : "male",
                  "phone": {
                      "mobile": "+91 0000000000",
                      "home": "00 000000",
                      "office": "00 000000"
                  }
          }
      ]
  }
  </code></pre>
  
  <p>Such data is normally parsed in java....</p>
  
  <p>My rabl view:</p>
  
  <pre><code>object @banks
  
  attributes :central_office_address, :license, :location_id, :name, :tax_number, :year_of_foundation
  </code></pre>
  
  <p>How do I change its output to match the second example?</p>