doc: rename to goembed
platform: generic interfaces for GPIO and SPI & creator functions

This is structured similarly to the github.com/ziutek/mymysql project
and how it has native and threadsafe drivers.
device: MAX31855: add comment about how I need to implement two's compliment
major refactor: put RPi specific bits in arch/raspberrypi

Use platform elsewhere.  Lets us port the same code from RPi to
BeagleBone, for example, hopefully...
device: max31855 renamed, as it is no longer linux specific!