When calling requestItemDelivery twice for the same uid, the second dbus call...

When calling requestItemDelivery twice for the same uid, the second dbus call would never be replied to,
and would just time out. Add reply to list, in order to remember to reply to it.
Also merge incoming requests with existing ones in more cases, not only when it matches the last one.

Based on patch by Tobias Koenig and input by Volker "Akonadi Master" Krause.

svn path=/trunk/KDE/kdepimlibs/; revision=1102360