GUI: use assign/remove method handling lists

- JsonUtils, added toList() method, which will return
  ArrayList<T> of required type from single object.
- Added call to assign and remove groups on resources.
- Use new methods on tabs, removed old methods handling
  single group-resource combination.
Merge pull request #156 from zlamalp/assign

GUI: use assign/remove method handling lists
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
Fix updateGroup ,method

- auditLog used not updated group instead of updated one
Merge pull request #158 from stavamichal/fix-update-group-method

Fix updateGroup ,method