Added debug -g to make CFLAGS for router
SansgridPeck payload handling fixes (IP-related)

SansgridPeck's SansgridSerial IP address needs to be broadcast, which
is a special case for payload handling. This has been taken into
account now.
Also added a little fix so that if rdid is somehow missing, the whole
router daemon doesn't crash
Updated tests to reflect modified peck handling

Peck's IP address can't be fetched from SansgridSerial, making it a
special case. It must be grabbed from the assigned_ip field in Peck.
The tests were updated to utilize this.
Cleaned up code in sg_serial_rpi.c

This is to prepare for another logic overhaul for sending/receiving
over SPI.

After the next commit, there should be a transmit buffer that outbound
packets are enqueued in, and all SPI transfers occur in sgSerialReceive.
Router should do Full Duplex SPI correctly now

Before, there were conditions where a full-duplex transfer would send
and receive valid packets in one transaction, then another transaction
would happen, sending and receiving invalid packets. Now a Transmit
buffer has been created, so a full-duplex transfer should involve one
and only one transaction.
Small fix for SPI code checking pending reqs

Before we wait for an interrupt, make sure nothing is waiting on the
transmit queue
Changed some documentation in router