SmartTable paging is not watching st-items-by-page

It seems that the smartTable directive is not watching the `st-items-by-page` value which leads to the case that when, by default, I have 10 per page, change it to 5 and then page to page two I will have again 10 results in my list.

In case of the usage of a `st-pipe` function it is possible to request results with an offset and a limit from the server by myself but the `params.pagination.number` shows me that my items per page value is getting lost whenever page.