Properly reset list item height after animation

Previously the list item height was reset to the pixel value it had
before the dismiss animation started. This could lead to wrong results
when wrap_content was used for the item height and the view was recycled
for another list item.
Now the layout height parameter is restored to its original value.
Merge pull request #14 from cketti/reset_list_item_height

Properly reset list item height after animation