Adding dragViewWithAccesibilityLabel:toViewWithAccesibilityLabel:

:warning: Not ready to be merged because of failing test case but I am looking for pointers. 

I need the ability to drag one view to on top of another - and I am considering of adding

```dragViewWithPoint:toPoint:``` and  ```dragViewWithAccesibilityLabel:toPoint:```

I could get my test case working using ```- (void)swipeViewWithAccessibilityLabel:(NSString *)label inDirection:(KIFSwipeDirection)direction```

But that only works if the direction is short enough for the swipe to work. However I can't get this to quite work, care to take a look at it?