[webui] Fixed add reviewer to submitrequests

- fixed switching user-, group-.... label
- fixed autocomplete methods
Switching search-params and adding reviewers works again, but the search-results are not visible in the dropdownbox. (I hadn't enough time to dig deeper in it, but I think it's a reason of the labels.) 
Unfortunately I'm on vacation for the next 3 weeks, so feel free to accept it for the moment or decline it.