(js) Drag'n'drop of cards in AddressBook module

Required to add the option to move multiple cards to another
addressbook. Fixed the possibility to copy cards to a subscribed
calendar.

UI/WebServerResources/js/Contacts/Contacts.app.js

@@ -110,7 +110,7 @@
       return addressbook.id == $stateParams.addressbookId;
     });
     if (addressbook) {
-      addressbook.selectedCard = false;
+      delete addressbook.selectedCard;
       addressbook.$reload();
       return addressbook;
     }