There is not need for a bootloader file to create an uninstall firmware so one
needs to provide a model.
Also cleanup the install script a bit by factoring message into a function, also
print them to the log so that the user can report what was printed on the screen
easily. The uninstall script is quite trivial, it remounts the rootfs and restores
the backed up OF to its right place.
Change-Id: I1f5c0efeb965fdc7fe17f45c2753c0f52c34f7f1
