Add copy_done check after first boot
Add copy_done check after first boot

This was previously removed because it failed on multi-image tests due
to some image having finished an upgrade and having it's flag already
set. A new method was added that checks that at least one copy_done flag
is unset, thus not all upgrades have finished.

Signed-off-by: Fabio Utzig <66676b1ceaf93296e098708c09494361103aa635@apache.org>

tamban01/mcuboot,utzig/mcuboot,tamban01/mcuboot,ATmobica/mcuboot,runtimeco/mcuboot,runtimeco/mcuboot,ATmobica/mcuboot,tamban01/mcuboot,runtimeco/mcuboot,ATmobica/mcuboot,utzig/mcuboot,tamban01/mcuboot,tamban01/mcuboot,runtimeco/mcuboot,ATmobica/mcuboot,utzig/mcuboot,runtimeco/mcuboot,utzig/mcuboot,utzig/mcuboot,ATmobica/mcuboot