heat engine : Resource remove redundant None get defaults

get(k) returns None anyway if k doesn't exist, so the default to
None is not needed

Change-Id: Id954c510a5c4795b5e0c3ccdcca186983dee2e8f
Signed-off-by: Steven Hardy <shardy@redhat.com>
heat tests : update_allowed_keys should be tuple

In test_resource.py update_allowed_keys should be a tuple not
a list, so it matches the expected usage in the resource classes

Change-Id: Ic7428e3790ea2c8c9887b464daf303c4f5d563fc
Signed-off-by: Steven Hardy <shardy@redhat.com>
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>