Add test for serverSide=true with xhr

When we render after xhr requests, we check against previous props to determine if we need another update to the UI. This test ensures that the check happens as it should and that the UI does update the display of data.

test/MUIDataTable.test.js

@@ -170,6 +170,21 @@ describe('<MUIDataTable />', function() {
     assert.deepEqual(JSON.stringify(state.displayData), displayData);
   });
 
+  it('should correctly re-build display after xhr with serverSide=true', done => {
+    const fullWrapper = mount(<MUIDataTable columns={columns} data={[]} options={{ serverSide: true }} />);
+    assert.strictEqual(fullWrapper.find('tbody tr').length, 1);
+
+    // simulate xhr and test number of displayed rows
+    new Promise((resolve, reject) => {
+      setTimeout(() => {
+        fullWrapper.setProps({ data });
+        fullWrapper.update();
+        assert.strictEqual(fullWrapper.find('tbody tr').length, 4);
+        done();
+      }, 10);
+    });
+  });
+
   it('should correctly re-build internal table data and displayData structure with prop change', () => {
     const shallowWrapper = shallow(<MUIDataTable columns={columns} data={data} />);
     let state = shallowWrapper.dive().state();