homescreens/halcyon: Change placeholder icon to arrow

Helps to teach users where the application list is.

containments/homescreens/halcyon/package/contents/ui/FavoritesGrid.qml

@@ -281,7 +281,7 @@ MobileShell.GridView {
             Layout.alignment: Qt.AlignBottom | Qt.AlignHCenter
             implicitWidth: PlasmaCore.Units.iconSizes.large
             implicitHeight: width
-            source: "emblem-favorite"
+            source: "arrow-right-double"
             color: "white"
         }
         
@@ -295,5 +295,9 @@ MobileShell.GridView {
             horizontalAlignment: Text.AlignHCenter
             text: i18n("Add applications to your favourites so they show up here.")
         }
+        
+        TapHandler {
+            onLongPressed: root.openConfigureRequested()
+        }
     }
 }