Updated header; logging now comma delimited

changed to comma delimited and changed the header to be more Matlab
friendly.  added comments in the header.  also, putting a comment about
the analogReference function in arduino language to assess the search
functionality of the github comments system.  I think it's possible to
set the analogReference to external and feed it the 5V out we're using
for the sensor excitation voltage, which may elimination the need for us
to log the excitation voltage separately.