add simple support for post.update to cfn-hup
add simple support for post.update to cfn-hup

Signed-off-by: Angus Salkeld <86b65304d27d8de73dd7d624c33df7e088f8d94b@redhat.com>

bbandaru/heat-cfntools,sdake/heat-jeos,openstack/heat-cfntools,steveb/heat-cfntools,steveb/heat-cfntools