Added valid invalid flag and read/write permission flag to DSObjectBase
The calling thread to getObject now removes itself as an observer on the local cache and synchronize calls now self invalidates all objects with readonly permission.
getObject now checks if the object requested is still valid before returning.
Added methods for removeObserver and selfInvalidate.
Added memory paramter to makefile
Commented out unneccessary prints
Removed classifier from putLocalObject
Changed self invalidate to loop through the correct objects