Adding a sanity check!

### Distribution build failing for Web Starter Kit

![Terminal failure screenshot](http://f.cl.ly/items/122h183n2F2r162d3O1m/Screen%20Shot%202014-12-18%20at%2010.58.23%20am.png)

Just wanted to check if we can add this sanity check here?

After adding this sanity, the build was smooth.

![Terminal success screenshot](http://f.cl.ly/items/2K2y1v1v19442U1n0L0M/Screen%20Shot%202014-12-18%20at%2011.07.00%20am.png)