Test paginator in Service Dialogs

* Basic test on Service Dialogs paginator
    * more complex after it starts working somehow that I can actually make the test
* accordion.tree in service_dialogs
    * includes flattening of the tree for faster navigation

**ATTENTION! This test is supposed to fail. I told you this.**

I am wondering of extracting the paginator lock detection into the paginator module.
Why 50 then 5? Does `results_per_page` need to do its job better?