Added Up and Down Modes to the panel.
Auto Still only picks left or right.
Middle will actualy come from any direction in a random fasion, looks quite cool, also means you can fling off the screen in any direction.
Updated demo to show the new modes.
Merge branch 'updown-pick' of github.com:Bizzby/android-sliding-layer-lib

Conflicts:
	Library/src/com/slidinglayer/SlidingLayer.java
Added in offset for up/down