Fixed pagination bug

There was a problem in that $.urlParam() returned 0 if there was no page param in the GET request. Django got the 0 parameter and because paginator.page(1) returns the first page, paginator.page(0) raised an EmptyPage exception which executed paginator.page(paginator.num_pages) delivering the oldest messages. So i changed the return 0 to return 1 in the javascript code.