revert api group test cases

Author: JacksonTian

test/api_group.test.js

@@ -48,7 +48,7 @@ describe('api_group.js', function () {
 
   it('moveUserToGroup should ok', function (done) {
     api.moveUserToGroup(puling, 102, function (err, data, res) {
-      expect(err).to.be.ok();
+      expect(err).not.to.be.ok();
       expect(data).to.have.property('errcode', 0);
       expect(data).to.have.property('errmsg', 'ok');
       done();