Added private method to check existence of meeting by ID
Added tests for getMeeting with id too high/low
for getMeeting, cast result to Meeting before returning.
Added test checking that getMeeting returns Meeting.
Added private method to update map of contacts to their meetings
Added first attempt of getFutureMeeting(contact) method.
Added outline of test for getting future meeting.
Currently have problem with getting the first element of the returned set. Once I figure this out I can check whether this element is the one that was supposed to be added.