raise StopIteration when no items are found on a page
bugfix: Top.path was returning None, Top.category is an int
raise StopIteration when no more items are found on page

for...else clausules aren't executed when the for is empty but when it
finished without a break. This way, we check for the first element,
raise StopIteration if not present, yield the first element and then all
the rest otherwise
make Paginated.next() return itself and define Paginated.previous()
parse explicitly 30 rows

On some cases, TPB returns their paginator into a tr, on others not.
This way, we always got the first 30 rows.
Merge pull request #23 from unaizalakain/master

raise StopIteration when no items are found on a page