Fixed uncaught TypeError

Without this fix it is not possible to unshare files/folders from the 'Shared' folder.
An uncaught TypeError occurred in line 343 because jQuery was looking for a tag with class="action delete", but in the 'Shared' folder this tag does not exist.
By using .children().last() the spinner will always be at the end of the row (just like in all the other folders) and unsharing works.