Fix 16u2 and 32u4 Bootloader bugs with Genuino

You currently added the Genuino files.
We recently (at least where I was involved) had some issues with the 16u2 firmware of the 16u2 and the 32u4 bootloader. There is some stuff that can be clearly improved.

The question is:
Is this .hex file already in production? Why dont you use this chance to update those firmwares/bootloaders to apply those fixes? I really would like to see this. I am also happy to help improve this, suggest solutions and give more information about what can/should be fixed.