title: grouping json data in a specific format
body: <p>My base data is as following..</p>
  
  <pre><code> [{
          month: 'Jan',
          cat: 'A',
          val: 20
      },{
          month: 'Jan',
          cat: 'B','
          val: 5
      },{
          month: 'Jan',
          cat: 'C',
          val: 10
      },{
          month: 'Feb',
          cat: 'A',
          val: 30
      },{
          month: 'Feb',
          cat: 'B',
          val: 10
      },{
          month: 'Feb',
          cat: 'C',
          val: 20
      }];
  </code></pre>
  
  <p>I need to convert it into the following using javascript preferably lodash..</p>
  
  <pre><code> [{
          selectedmonth: 'Jan',
          data:[{
          mycat: 'A',
          myval: 20
      },{
          mycat: 'B',
          myval: 5
      },{
          mycat: 'C',
          myval: 10
      }
         ]
      }, {
          selectedmonth: 'Feb',
          data:[{
          mycat: 'A',
          myval: 30
      },{
          mycat: 'B',
          myval: 10
      },{
          mycat: 'C',
          myval: 20
      }
         ]
      }]
  </code></pre>
  
  <p>I understand the lodash groupby - month call would do the groupby but it does it in a different format..</p>
  
  <p>Any help is sincerely appreciated..</p>