There is now a mangoh_red and a mangoh_green module.  The universal
mangoh module did very little in terms of code sharing so it made
sense to split it into two simpler modules.

The goal was to remove explicit paths where possible.  In the case of
the submodules, this helps to make them more useful as a standalone
repository in case a use isn't interested in cloning the whole mangOH
repository and all of the submodules.

Also updated the developerDay2016 tutorial app to use AVC 2.0 so that
it will work with Legato versions 17.05 and newer.

Remove the commented out gpio initialization code because it doesn't
seem like the gpio interface of the wp85 kernel will change in the
short term and thus the gpio kernel driver isn't useful.

Update comments in Makefile to support Developer Studio

There is an issue where the cp2130 usb to spi adapter chip gets into a
bad state and locks up the USB hub.  Don't enable the module until we
can resolve this issue.