GUI: support for observer role

 - allow to display vos/members tab
 - vo and members are clickable for new role
 - added support in session

TODO: groups tabs, content of all tabs, where vo_admin or vo_observer.
GUI: more support for VoObserver role

- VoObserver can now browse all tabs like vo admin, but all buttons
  and table checkboxes should be disabled.
- Tabs for add/assign/edit are not accessible for new role.
- Added new method to JsonCallbackEvents which can be used to pass data
  (results) from one callback to another.
- Added some custom messages for empty tables to vo/group management.
- Code format and cleanup.
GUI: more custom texts on empty tables

- Added more custom texts displayed on empty tables.
- Source format.
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.
CORE,REGISTRAR,RPC,GUI: privilege fixes for VOOBSERVER

CORE:
- Added privilege to list vo's groups and vo/resources tags.

REGISTRAR
- Added privilege to list applications of VO/Group/Member.
- Added authz for getting application form item.

RPC:
- Registrar interface changes (pass session).

GUI:
- Fixed authz in various places, disabled some more action buttons.
GUI: better custom empty table texts

- More custom empty table texts respect filtering
- Added filtering above facility resources by resource name
  or vo name/shortName
GUI: usability fixes

- Added custom empty table messages also to facility manager
  part of GUI + rest of tabs.
- Added filtering above Tasks (by service/type) on facility detail.
- Fixed menu refresh on PerunAdmin/Facilities tab.
- Source format.
GUI: pass groupId to members tabs for better authz

- Pass groupId if member's detail is displayed from group detail context.
  Resulting in more precise authz.
- Fixed empty table messages in members applications, settings tabs.
- Other small fixes to buttons and UI.
GUI: unified UX for application form settings table

- Application settings table should now look even more like others.
  All messages are display inside table (even when form doesn't exists)
  and menu is disabled but displayed.
- Source format.
GUI: allow to list all members when adding them to group

- Added "List all" button to AddMemberToGroup tab.
- Reworked implementation of search/listAll vo members
  so buttons are properly disabled when any action is active.
- Redesigned addMemberToVo tab, button order + shows already added.
- Added triming of input for TabMenu search widget.
Merge pull request #181 from zlamalp/observer

Support for VoObserver role + usability and design fixes in GUI