Only allow adding items which are supported by backend in calendardemo
Only allow adding items which are supported by backend in calendardemo

Previously, menu options to add an item of each particular type were
provided regardless of whether the manager supported items of those
types.  This commit checks to see whether the item type is supported
before adding the menu option.

Task-number: QTMOBILITY-747
Reviewed-by: Charles Yin

tmcguire/qt-mobility,enthought/qt-mobility,KDE/android-qt-mobility,qtproject/qt-mobility,kaltsi/qt-mobility,kaltsi/qt-mobility,tmcguire/qt-mobility,kaltsi/qt-mobility,KDE/android-qt-mobility,qtproject/qt-mobility,tmcguire/qt-mobility,enthought/qt-mobility,kaltsi/qt-mobility,kaltsi/qt-mobility,KDE/android-qt-mobility,enthought/qt-mobility,KDE/android-qt-mobility,tmcguire/qt-mobility,enthought/qt-mobility,qtproject/qt-mobility,enthought/qt-mobility,kaltsi/qt-mobility,enthought/qt-mobility,qtproject/qt-mobility,tmcguire/qt-mobility,qtproject/qt-mobility,qtproject/qt-mobility