Added code for an aperiodic task queue
Renamed file.
Added class to handle polling server schedules.
Updated logic.
Added logic for Deferrable Scheduler.
Updated test cases.
Updated Deferrable Scheduler logic.
Updated test cases and added comments.
Updated documentation.
Updated simulator gui to work with new schedulers.
Removed old files.
Removed old test file and updated schedulers to use an abstract class.
Added background scheduler.
Updated gui.
Updated logic in schedulers and gui.
Updated constructor of abstract scheduler class.