Fixes: Change CalendarModelBehavior to public class and make it customiz...

Fixes: Change CalendarModelBehavior to public class and make it customizable in the Calendar object so that you can overwrite the behaviour

For instance by overwriting the CalendarModelBehavior onRequest method you can modify the Date to be Timezone safe / send in another timezone.

This is a pull request for Apache Openmeetings, we have custom timezones in our user profiles and need to display the Calendar UI in a different timezone (different from User and different from Server timezone)

For any questions please contact: seba.wagner@gmail.com or sebawagner@apache.org or visit our mailing list at: http://openmeetings.apache.org/mail-lists.html