Fixed pagination bug

That function was unnecessary because it was called only when switching between tabs and when this happens, i think it would be normal to provide the user with the newest messages. Also, because when switching between tabs there was no page parameter in the GET request, the function returned 0, which in turn raised a EmptyPage exception on django(paginator.page(1) returns the first page, not paginator.page(0)) and in this way the oldest messages were returned to the user.