Models get updated when userData changes at server

The websocket now notifies the ApiClient, on which several models and
items are listening, when the userData for an user has changed. The UI
on the qml side may automatically updates without any extra effort.

This also resolves a bug where videos didn't resume after +/- 3:40 due
to an integer overflow.

sailfish/qml/components/LibraryItemDelegate.qml

@@ -86,5 +86,6 @@ BackgroundItem {
         height: Theme.paddingSmall
         color: Theme.highlightColor
         width: root.progress * parent.width
+        Behavior on width { SmoothedAnimation {} }
     }
 }