Add Shimano Di2 shift count support and Edge sweat loss units

[jheexyz]

I am not skilled enough to make changes here (yet), but I found that editing my download of the FIT.pm file to make this diff then the fitdump output shows Di2 shifting counts and the Garmin Edge1030 sweat loss summary:

5261,5262c5261,5262 < 107 => +{'name' => 'front_gear_change_count'}, < 108 => +{'name' => 'rear_gear_change_count'},

 107 => +{'name' => 'unknown107'}, # unknown UINT16
 108 => +{'name' => 'unknown108'}, # unknown UINT16

5291d5290 < 178 => +{'name' => 'sweat_loss', 'unit' => 'ml'},

I hope that someone might add this to the code so it would be useful to others.