fixing bug #4727 GED Impossible de modifier la date de visibilité
Merge branch 'bug-4727' of git://github.com/CecileBONIN/Silverpeas-Components into CecileBONIN-bug-4727
Bug #4727 : the correction applied by Cecile was good.
But in fact, the integration of a new useful checker plug-in of dates had been dropped (unintentionally i hope) during a merge operations of feature #82 with some conflicts ...
So i have restored the call of this new plug-in.