This closes #12.
This closes #12.

Merge remote-tracking branch 'd3zd3z/verify0'

* d3zd3z/verify0:
  Validate slot zero before booting

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