FOTA from Conduit gateway

If wanting to implement the FOTA capability on a custom LoRaWAN end node, here are some key points for the Conduit:

1. The Conduit sends down 0-based frame index.
2. The Conduit uses an McKEKey of all zeroes.
3. The Conduit CRC confirmation is sent on port 201 (Fragmentation port) and uses 0x80. So after the end node has reconstructed the file the end node will calculate the CRC, and send the CRC on port 201 with first byte 0x80 then CRC. The Conduit will respond with 0x8001 (hex bytes) if correct on port 201, or 0x8000 (hex bytes) if incorrect on port 201.

Notes: Point #3 will be addressed in a future release.