OpenAPS system tray with cover, LiPo/ERF

I switched to an ERF radio shortly after designing my last OpenAPS case (http://www.thingiverse.com/thing:1525618), so I decided to try again.

Design goals this time around:

- Smaller
- Lighter
- Access to console port
- Access to power button
- Easier to open
- Easier to build
- Easier to print

This new case is 52mm x 21mm x 65mm and 92g fully assembled, which may not sound like much of an improvement, but which yields a device that feels significantly smaller and less bulky.