Oculus abc viewer

Includes the previous pull requests as well.

This copies the SimpleAbcViewer into another directory, called OculusAbcViewer, and adds in the pieces needed for a simple integration with the Oculus Rift SDK.  It works in the same way as the SimpleAbcViewer - the same mouse commands, you can frame the camera, but the rendering is done through the oculus SDK.

The additional argument is to scale the inter-pupillary distance for scenes that aren't 1 unit = 1 meter (--scale).

What you should see is when rendering is something like this:
![screen shot 2014-08-05 at 5 36 15 pm](https://cloud.githubusercontent.com/assets/61017/3820966/b31217a6-1d01-11e4-9c94-de495d4ef3bb.png)