incorrect evaluation of members property

[Stephen Gran]

When evaluating an OS::Neutron::Loadbalancer, if the members property is absent, it currently defaults to None.

This make constructs like

for member in self.properties.get('members', []):
     ....

Fail, since what is returned is None rather than [], as self.properties has a key 'members' with a value of None.

The default should be changed to an empty array so that we don't have to keep guarding against None.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/58797
Committed: http://github.com/openstack/heat/commit/a028cbe46cb22b050af3f3131dde8655f6ebc852
Submitter: Jenkins
Branch: master

commit a028cbe46cb22b050af3f3131dde8655f6ebc852
Author: Stephen Gran <email address hidden>
Date: Wed Nov 27 15:40:47 2013 +0000

    Ensure that members is a list

    self.properties.get('members') should not be None. Ensure that
    an empty list is returned instead.

    Change-Id: I01d191eafebac30ad25505b312ff6e936181bdbf
    Closes-Bug: #1255697