title: Add / Remove row(s) in ag-grid
body: <p>How to add or remove a row in ag-grid,<br />
  i try this, but not work</p>
  
  <pre><code>$scope.gridOptions.rowData.push(data);
  </code></pre>
  
  <p>and with this</p>
  
  <pre><code>scope.gridOptions.api.forEachNode( function(node) {
      var data = node.data;
      updatedNodes.push(vehicle);
  });
  
  $scope.gridOptions.api.refreshRows(updatedNodes);
  </code></pre>
  
  <p>Thanks</p>