Stupid Newb question I am sure, but ... I have a few MP3's I want to use as Ringtones on my Nexus, but they do not auto loop like the existing ringtones do. How do I make them play continuously like all the included ones do? Instead of a continues song like "Enter the Nexus" or any of the other ringers that come with it, I get several second long gaps between plays of the MP3. Thanks!