Raspberry Pi model B robot chassis

A chassis designed for building a simple and cheap Raspberry Pi robot, using the 'standard' motors and wheels that come with kits like the excellent [CamJam EduKit #3](https://camjam.me/?page_id=1035). It has a space at the front for a mini breadboard so that you can mount sensors or LEDs. Motors can be powered by 4x AA cells in a standard case while the Pi itself can be powered by a phone power bank. Slots are included in the chassis to house both of these. Example worksheets and code can be found [here](https://github.com/topshed/PiBots)