Use long date format when expanded

app/src/main/java/eu/faircode/email/AdapterMessage.java

@@ -108,7 +108,7 @@ public class AdapterMessage extends PagedListAdapter<TupleMessageEx, AdapterMess
     private boolean avatars;
     private boolean debug;
 
-    private DateFormat df = SimpleDateFormat.getDateTimeInstance(SimpleDateFormat.SHORT, SimpleDateFormat.LONG);
+    private DateFormat df = SimpleDateFormat.getDateTimeInstance(SimpleDateFormat.LONG, SimpleDateFormat.LONG);
 
     enum ViewType {UNIFIED, FOLDER, THREAD, SEARCH}