Fixing the recurrence panel not showing inside the floater.

The initialization for the floater showing was done only on page load,
while the floater itself was loading later via AJAX. Hence initialization
was missing. This is now done every time the floater loads.
Cleaning the recursion deadline when its option is set to disabled.

A user might have first chosen to end a recurrence on a specific date, but
then changed her mind and switched off the deadline. This should clear the
value as well to avoid confusion and make sure the value doesn't getsent
to the app and stored.