For opcodes with 0x42 return value, where we retrieve data_bank information, the first message should have a 0x70 "command", while subsequent messages should have "0x60" for the command.  This seems to be related to getting more detailed informaiton from the tracker.  I noticed this through careful reading of the fitbit software logs, and it appears to be getting the full info now.
For opcodes with 0x42 return value, where we retrieve data_bank information,
the first message should have a 0x70 "command", while subsequent messages
should have "0x60" for the command.  This seems to be related to getting
more detailed informaiton from the tracker.  I noticed this through careful
reading of the fitbit software logs, and it appears to be getting the full
info now.

Also, after sending a payload, or after returning 0x41, pass the received
response back as the result instead of synthesizing a dummy response.  I
don't know if this really makes any difference, but it seems more "honest"
with the fitbit website.

openyou/libfitbit,kalon33/libfitbit