Missing fling feature

[znakeeye]

If the goal is to mimic the way Launcher does this, I believe there are two errors in HorizontalPager.

1. FRACTION_OF_SCREEN_WIDTH_FOR_SWIPE should be set to 2.
2. Fling motions should trigger a view swipe when acceleration is high enough (1000 pixels/sec?).

For this we need a GestureDetector. I'll try to implement this tonight.