build: edify: use set_metadata for backuptool

Also use saner permissions on backuptool.sh

Change-Id: I50742b51867aa358f5924b8dc208833092a35bd9
build: use /usr/bin/env to call python

Hardcoding the path to python instead of env is not recommended.  This
can break the build in some Linux environments that link /usr/bin/python
to python3.

Change-Id: I4c62eb391acc6d468ce24ac8640834e965e76e78

Conflicts:
	tools/getb64key.py