uce.hrl: Set  a default parameter from null to none.
uce.hrl: Set  a default parameter from null to none.

The uce_meeting start_date and end_date parameters are now set to none by
default.

AF83/ucengine,stormz/ucengine,stormz/ucengine,stormz/ucengine,stormz/ucengine,AF83/ucengine,stormz/ucengine,AF83/ucengine,AF83/ucengine