Updates to include latest nordic sdk and ARM support

This modifies the Adafruit nrf8001 driver code as well as minor modifications to the Adafruit Bluetooth UART service code. 

Modifications include receiving boolean status of whether a byte or buffer was actually sent (original code assumed that if no exception was thrown then write was succesful).

Includes nordic sdk message queue for reads and writes (can probably remove articial 35 ms delay). 

Support for Teensy and non-avr hardware.