SPI!

We've finally gotten SPI communication working between a FireFly node and the HC12.  Our goal with this was to transfer accelerometer data to the HC12, which would handle the grunt work of powering the motors.  Right now it's only one-way communication, but if we find other uses we could make the line bidirectional as well.  Our thanks to TA Sanket for help, he taught us SPI and found the source of the bug that kept the system from working: the NRK_DEBUG_0 port wasn't actually outputting any signal.  Now that this step is done, we've got to write the code for the HC12 that uses this accelerometer data to move the car around.  Maybe we can find why RT-Link isn't working so well either...