RoundRobinAutoCompletion - show an info label for each CompletionProvider #41

I'm moving RSTA #166 to here. From @eitzenbe:

For the round robin AC it would be cool to have the option of displaying a label for each provider currently shown:
something like adding a set/get name method to the CompletionProvider interface, that is then used by the AutoCompletion to add a JLabel with that name to the contentpane of the AutoCompletePopupWindow , as it is a BorderLayout -> contentPane.add(JLabel, NORTH)