OmniSwitch: fix IndexOutOfBoundsException

This might not be the final solution but for now
fix the crash

05 17:54:17.560 E/AndroidRuntime(18708): java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
04-05 17:54:17.560 E/AndroidRuntime(18708):     at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:255)
04-05 17:54:17.560 E/AndroidRuntime(18708):     at java.util.ArrayList.get(ArrayList.java:308)
04-05 17:54:17.560 E/AndroidRuntime(18708):     at android.widget.ArrayAdapter.getItem(ArrayAdapter.java:337)
04-05 17:54:17.560 E/AndroidRuntime(18708):     at org.omnirom.omniswitch.ui.SwitchLayout.onDismiss(SwitchLayout.java:326)
04-05 17:54:17.560 E/AndroidRuntime(18708):     at org.omnirom.omniswitch.ui.SwipeDismissHorizontalListViewTouchListener.onAnimationEnd(SwipeDismissHorizontalListViewTouchListener.java:408)
04-05 17:54:17.560 E/AndroidRuntime(18708):     at android.animation.ValueAnimator.endAnimation(ValueAnimator.java:1056)
04-05 17:54:17.560 E/AndroidRuntime(18708):     at android.animation.ValueAnimator.access00(ValueAnimator.java:50)

Change-Id: Iea4e5f8883b9d291091a901ff94637b11c3c5b0f