add tool to flash binary

I tried to place the sources for this tool in this project but I failed.
This is almost impossible because it requires to migrate the entire MEN
chameleon framework, fixing its bugs when using modern compilers, and
many more issues.

We already have a binary that works, and it is statically linked. It
will work "everywhere".
Signed-off-by: Federico Vaga <federico.vaga@cern.ch>