Update to Handlebars v2.0 as required by 1.9.

V1.9.0 needs handlebars v2.0.0: 
![screen shot 2014-12-10 at 11 52 55 pm-1](https://cloud.githubusercontent.com/assets/744/5386150/2fa51522-80c9-11e4-8bc4-64960b392b47.png)