Updated gradle files
Created AnimateAdditionAdapter
Created Animate Addition example
Merge branch 'dev' into pr/n104_WonderCsabo
Merge branch 'pr/n104_WonderCsabo' into dev

Fixes #104
Check a DeleteItemCallback is set before accessing it. Fixes #105
Enforce providing a DeleteItemCallback when creating a new ContextualUndoAdapter. Fixes #111
Use consistent indentation (4 spaces instead of tabs). Fix 106.
Created AdapterViewUtil#getPositionForView(AdapterView, View) which should be used instead of directly calling AdapterView#getPositionForView to take headerviews into account.  (Note: DynamicListView does not use this method). Fixes #105
We're only measuring GridView items if we're actually showing a GridView. Possible fix for #112.