Updated openstack/openstack
Project: openstack/heat  4950b0b03f7e757856ccd8426bc4b494733b659f
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Let resources decide when to update

Previously, the StackUpdate code decided when an update was necessary for a
resource. However, all of the information required to make this decision is
available to the resource, so push this decision into the resource so that
it can implement custom behaviour if necessary.

Change-Id: If098424cf2502c02bad4194d509393d198d8745f