Add Raspberry Pi device (#1501)

aports/device/device-raspberry-pi/95-vchiq-permissions.rules

aports/device/device-raspberry-pi/APKBUILD

aports/device/device-raspberry-pi/cmdline.txt

aports/device/device-raspberry-pi/config.txt

...-raspberry-pi/device-raspberry-pi-kernel-rpi.post-install

...raspberry-pi/device-raspberry-pi-kernel-rpi2.post-install

aports/device/device-raspberry-pi/deviceinfo

aports/device/device-raspberry-pi/usercfg.txt

pmb/config/__init__.py

pmb/install/format.py

pmb/install/partition.py

test/test_aports.py