cf-key -s has its special sig handler but the other operations need one too

(cherry picked from commit 11d058f86682aff4e0a855e86d37947e6f4b371c)
cf-key -s has its special sig handler but the other operations need one too

(cherry picked from commit 11d058f86682aff4e0a855e86d37947e6f4b371c)

added debian directory to build deb packages
Merge branch '3.6.x' of https://github.com/cfengine/core into 3.6.x
Merge branch '3.6.x' of github.com:basvandervlies/core into 3.6.x

Conflicts:
	debian/cfengine3.default
	debian/changelog
	debian/postinst