Added enableEmptySections flag for calendar list view

Given an empty list, the ListView component would give a warning. With this flag set, it doesn't.

app/components/Calendar.js

@@ -26,6 +26,7 @@ const Calendar = (props) => {
       <ListView
         dataSource={dataSource}
         renderRow={rowData => rowData}
+        enableEmptySections={true}
       />
     </View>
   );