GUI: VO management usability fixes

- Custom texts in Vo tables now offer different message, when
  filtering on table is active. Because there is difference
  between "Vo has no members" and "No member matching 'sth' found.".

- Fixed styling of Application Form Settings table, so it now
  looks like other tables used in GUI. Display message when
  form exists but has no form items. Also form items which
  contain tables no longer display unnecessary border.