Drag&Drop on api21

[szoszig]

I encountered a little wierd problem, with this lib.
It works perfectly with any other api version I tried, but with api 21 it "disables" the drag&drop functionality.

In ItemTouchHelper class, there is a method, called "moveIfNecessary", it always returns on the first condition, therefore onMove never get called.
I tried different support versions too.