This adds a new protocol extension which allows to get the bootloader
version.
The bootloader version is different from the bootloader protocol
revision which has stabilized at 5 and is not easy to update unless a
bootloader is actually breaking the protocol. The reason being that both
the Python script as well as the uploader used in QGC will not attempt
to load firmware if they don't know the bootloader version, so it could
basically be considered a "breaking" protocol revision.
Signed-off-by: Julian Oes <julian@oes.ch>
7c4507b6d6