General changes

- Start class re-activated, used to properly configure log4j
- Updated build.xml: added doc, clean-doc (for javadoc generation)
targets, added copying of log4j.xml file
Controllers/Model updated

- Fixed a bug in the EventsController which caused the Event to not
properly update Dates/Participants/Comments (as it reset to a state
before it got changed).
- Improved Documentation in NotificationsController/ControllerProxy and
SessionManager and several Model classes
- The parameterized constructor in Event will now initialise the
Collections
- Added Documentation to IViewElement
- Fixed TestNotificationController asserting the wrong return value
- Small fixes in TestSessionManager
View implementation

- Added missing Listeners
- Fixed Login/Register Listener
- Completed NewEvent Listener
- Added Invitiation, Notificatio Handling
- Added Event view
- Added Date voting & fixing