Operational space control example

Implementation of simple operational space control example

Reference: [Synthesis of Concurrent Object Manipulation Tasks, Section 5.1](http://www.cc.gatech.edu/~ybai30/multitask/multitask.pdf)

![image](https://cloud.githubusercontent.com/assets/4038467/4985099/b6db37c2-6929-11e4-8e4a-fb5e7efc315f.png)