Persist todo items in localStorage
(fix bug): ngRepeat was failing due to duplicate elements
(fix bug): The remove button stopped working

The reason the button stopped working was due to the fact that when
we retrieved the list of todos from localStorage within the directive
it would be instantiated as an entirely new object and so the way we
were searching for matching todo items meant that we couldn't find
the one we clicked on because it was created an stored in an entirely
separate list.