adding uEnv.txt from Jonathan to setup all the device tree overlay setup work upon boot.
Joanthan Instructions:
"I have enclosed the uEnv.txt that you to copy in place of the one in /boot/uboot on the beaglebone-black. This file will wipe the emmc and disable it. It will also unload hdmi at startup. I have uploaded a new version of the camera demo for the logibone on logi-apps"