Select OLED settings based on platform

* Use platform name to determine if the platform is Mendel Linux.
  If so, use Coral Dev Board valeus and RPi.GPIO wrapper for
  periphery. Otherwise, assume Pi and use defaults for Luma.
* Run autopep8 on coral-enviro

Change-Id: I035d2a4bf17ebb79a4180f65d9c4f6791badba6e
3 files changed