[2.3] GRID - Fix sort menu padding

Before:
![property sets modx revolution](https://cloud.githubusercontent.com/assets/825106/3551210/970c0a44-08e3-11e4-8c7e-f9023056b5c2.png)

After:
![property sets modx revolution_after](https://cloud.githubusercontent.com/assets/825106/3551215/a08d72c4-08e3-11e4-9036-9858ebf5f5e6.png)