Fix date format parsing

I came across this bug because "Waiting List" was not sorted properly. Then i realized it was a date parsing problem with some feeds.

Short year format specification works in both cases. Long year didn't. You can check docs if you want:
http://docs.oracle.com/javase/1.4.2/docs/api/java/text/SimpleDateFormat.html#applyPattern(java.lang.String)

The code has been tested with both types of year spec:
- Long format like "2013", which worked both before and after the patch. Eg: http://feeds.feedburner.com/droidcast/
- Short format like "13", which parsed nonsense timestamps before patch and now works. Eg: http://www.ivoox.com/portada-ivoox_fh.xml