fixed typo and added comments to load()
added constructor for meeting with notes
updated addPastMeeting() to allow for notes being added at construction
tests for null input to addNewPastMeeting()
updated addPastMeeting() to confirm that all contacts are know
check for empty Set of attendees as parameter to addNewPastMeeting()
check for empty Set of attendees as parameter to addNewPastMeeting()
Test for unknown attendee in Set parameter to addNewPastMeeting()