Fix for crash  :

E/AndroidRuntime(24835): FATAL EXCEPTION: main
E/AndroidRuntime(24835): java.lang.NullPointerException
E/AndroidRuntime(24835): 	at com.namelessdev.mpdroid.fragments.PlaylistFragment.trackChanged(PlaylistFragment.java:448)
E/AndroidRuntime(24835): 	at com.namelessdev.mpdroid.helpers.MPDAsyncHelper.handleMessage(MPDAsyncHelper.java:134)