Write code to flash firmware onto the nRF51822

[dhylands]

We'll need to be able to update the firmware on the nRF51822.

The best way is to actually have the cc3200 act as a programmer and use the SWDIO/RESET and SWDCLK signals.

I found some code which implements the protocol needed for flashing here:
https://github.com/cbiffle/swddude

Unfortunately, it seems to be in C++, but at least the algorithms should be there. It also supports way more stuff than what we need (i.e. programming via FTDI etc).

I'd recommend that we reimplement in rust or C and we'll just wind up bit-banging GPIO signals.