heat engine : Resource add function to compare properties

Add update_template_diff_properties to make comparison of
pre/post update resource properties easier

Change-Id: Ic37d37ae510a62739d4cc4219cfd69479a87767d
Signed-off-by: Steven Hardy <shardy@redhat.com>
heat engine : AutoScalingGroup UpdateStack support

Adds improved UpdateStack support for AutoScalingGroup,
now the following properties can be updated without
replacement:
'MaxSize', 'MinSize', 'Cooldown', 'DesiredCapacity'

Change-Id: Ic47b4a2456dc19cd91eec7b0381d5d82fcd3f332
Signed-off-by: Steven Hardy <shardy@redhat.com>