Fixed stupid bug (read the doc, man!)

Thanks, val.
> val │ random.shuffle does not return anything
> val │ so:
> val │     random.shuffle(items)
> val │     return items
> val │ I lost count of how many times i made this mistake...

plugins/RSS/plugin.py

@@ -172,7 +172,8 @@ def sort_feed_items(items, order):
     if order == 'asInFeed':
         return items
     elif order == 'random':
-        return random.shuffle(items)
+        random.shuffle(items)
+        return items
     (key, reverse) = _sort_arguments(order)
     try:
         sitems = sorted(items, key=key, reverse=reverse)