New failing e2e test for adding new activity links
New failing backend unit test for addActivityLink method
Working backend.addActivityLink (for links with new people only)
Getting the creation of new activityLinks working. Can create links with both existing people and new ones (with dummy nodes).
Changed the graph to redraw every time it is viewed (to make sure newly added nodes and links are drawn and arranged correctly).
Also adding a basic alert handler that makes it easier to show messages to the user.