GUI: logout from application form gui

- Added logout link to menu in application form.
- When form is submitted, but not stored (hard error),
  allow users to get back to app form without losing
  what they already filled in.
- Code simplification in logout widget.
- Clear shibboleth cookies method is now in Utils.
- Fixed "Go to perun web" button align on logout widget.
- Prevent accidental close of error reporting widgets created
  by json calls when clicking outside of the box. User must select
  desired action by click on button. This ensures, that user will be
  able to read error message.
- Source format.