fixes #5773 - redirect to referrer URL that includes page and search

Would it be crazy to add it to every controller that supports search?  This could be done through the AutoCompleteSearch mixin, editing process_success so it uses the saved URL if available in that controller, and updating any other instances of :success_redirect.

The only downside I can think of is that there might be bits of the application where people do a search to find a resource and don't care any more about the search after saving.  @ohadlevy what do you think?