Use NineOldAndroids library to make Drag and Drop and the example app to work on API 8 or higher.

Fix running example app on Emulator without Google Play Store.

Fix most problems with drag&drop on API levels < 14.
Also contains fix for #254

refresh mMobileView only when needed.

Fix visible mobileView when dragging on API < 14.

This works only when SimpleSwipeUndo is enabled too. When it's not enabled the mobileView remains is visible.

Some cleanup, fixed scroll item swapping.