Refactored how updates are handled, now when there is a change the client is told to update there local copy with the specific change, rather than resend either the whole list of employees information, or the whole list of shift information. This change to updates should make changes to the staff or schedule more efficient especially when there are multiple clients.
In coming data from the server is now stored in HashMaps where the key is either the shift or employee IDs, and the value is of Shift or Employee classes.
All the methods in this class were made to help with these 2 changes.
Cleaned up warnings.