changed pin map in Ghost to [(physical_location, pin_instance)...]
added pin location to Pin
added location argument and attribute to Pin and DigitalPin
changed logical_id to gpio_id
refactored _list_pins and _base_pin_path
started pcduino driver
Merge and rebase. Then, fixing Raspberry Pins. Adding 'location' to VddPin(). Including a Vdd and GroundPin on Ghost