title: Add child stories to EPIC story cardboard
body: <p>I have created a board of EPIC stories filtered by target release using Rally App SDK. I would like to display child stories info (Formatted ID and Name) for each epic story in the board and I'm not sure how to do that. Anyone know of a simple way to add this to each of the cards? Please see my code below:</p>
  
  <pre><code>            _onLoad: function() {
                  this.add({
                      xtype: 'rallycardboard',
                      types: ['User Story'],
                      attribute: 'ScheduleState',
                      readOnly: true,
                      context: this.getContext(),
                      cardConfig: {
                          editable: false,
                          showIconsAndHighlightBorder: false,
                          fields: ['Name', 'TestCases', 'c_StoryType', 'Children', 'c_TargetRelease', 'PlanEstimate']
                      },
                      storeConfig: {
                          filters: [
                              {
                                  property: 'c_StoryType',
                                  value: 'SAGA Feature'
                              },
                              {
                                  property: 'c_TargetRelease',
                                  operator: '=',
                                  value: this.down('rallyfieldvaluecombobox').getValue()
                              }
                          ]
                      }
                  });
              },
  
              _onSelect: function() {
                  var board = this.down('rallycardboard');
                  board.refresh({
                      storeConfig: {
                          filters: [
                              {
                                  property: 'c_StoryType',
                                  value: 'SAGA Feature'
                              },
                              {
                                  property: 'c_TargetRelease',
                                  operator: '=',
                                  value: this.down('rallyfieldvaluecombobox').getValue()
                              }
                          ]
                      }
                  });
              }, 
  </code></pre>