Revert "Added ability to have multiple definitions for a single property"

This was a hack build around the inability to process 'OR' in queries.
We start implementing 'OR'

This reverts commit b25f5f9688f22c70a4348a41afe321447908fdc5.
Fixed a few NPEs arising from recent node-dependency changes
Updated MemoryTest to use world.properties instead of init.properties
Added method clone() to Result class to create a deep-copy
Working on AND | OR handling