Resource.__eq__ allow resources in different stacks

Resource.__eq__ allow resources in different stacks

Doing a stack update was incorrectly replacing identical resources
because Refs in the new resource were evaluating to None in the new stack.

This change allows an alternative template to be passed to parsed_template
and modifies __eq__ to compare the two templates in the same stack.

__eq__ now also checks that the name of both resources matches, since a stack
could have multiple identical resources with different names.

Change-Id: I7e09ee1238dd01490cdfe186c51b7fada9546a63