added functionality to addFutureMeeting and getPastMeeting methods
added private methods to generate IDs
added set up and tests for addFutureMeeting and getPastMeeting
changed signature of add contact method to allow for testing
added testing for adding new contacts and getting contacts into a list based on IDs provided
code for methods to add new contact and get existing contacts into a set added
changed signature of addNewContact method to allow for testing