Work done: * Completed implementation of generic monitoring framework fo...

...r seep. * Modified QueryPlan, QueryComposer and QueryBuilder to allow specifying scaling policy rules along with the operators and plan for the query. * Instrumented seep runtime (InputQueue). * Removed unnecessary classes. * Modified config.properties file to use light-state instead of large-state for checkpointing. * Added if statement in CoreRE class to check that processing unit is of type StatefulProcessingUnit before attempting to cast it (to prevent ClassCastException). * Created unit tests especially around new generic monitoring framework.