Update for the back piece of thing:92208 to fit v2.1 of the raspberry pi camera.

The v0.4 back piece has been modified to better fit the v2.1 pi camera:

• The mounting posts have been moved closer together. They were originally too far apart for the holes in the camera board.
• The sides have been cut out to allow room for the additional electronics on the underside of the camera board.

This piece of the case should work with any other thing that uses the original case front and needs to fit a v2.1 pi camera board.