GUI: fixed add member to group / add manager dialogs

- Do not display ", " after name of last added user.
- Auto-select single result when search for people
  to be managers of group/vo/facility.
- Fixed implementation which cause not refreshing
  table content when search results were empty.
- Source clean-up and format.
Merge pull request #157 from zlamalp/group

GUI: fixed add member to group / add manager dialogs