List.UniqueItems now works for all kinds of object: MAGN-3907

@aparajit-pratap @riteshchandawar

![unique](https://cloud.githubusercontent.com/assets/1699155/3739360/ffa91302-1749-11e4-93fb-352e33bef61d.PNG)

I am wondering if it's going to work for two different instances of the same object.
{new Point(), new Point(1,0), new Point(1, 0)} ?? It may work only if the Hash code is same for both the instances.