Made a very minor refactor to the Resource system.  Moved the ResourceManager into the Resource namespace.  The manager files and the namespace header were moved to the Resource folder.  Removed ResourceInputStream.  Created an AssetID class for sticking assets in associative containers.  Moved most of the static members on the ResourceManager class to free functions in the Resource namespace, in the resourceutilities.h header file.  Beefed up the AssetGroup class to provide very basic functionality of what is planned in it's future.  Updated the rest of the engine to use the updated resource API.
Updated EntreLua for the resource system changes.
Updated UnitTests for the resource system changes.