REGISTRAR, GUI: exception on missing federation data

- Throw exception when retrieving application form for user
  and his/hers IDP doesn't provide data for required form items.
REGISTRAR, GUI: updated display of missing data widget

REGISTRAR:

- Throw exception after all items are processed to send
  all missing form items (do not multiple resolve issues 1 by 1).

GUI:

- Custom display of error on app form page.
REGISTRAR: fixed fed attributes check

- Throw exception only if user is logged-in by IDP ext source.
- Throw exception only if form item is not editable to user
  (FROM_FEDERATION_HIDDEN, FROM_FEDERATION_SHOW).
Merge pull request #206 from zlamalp/registrar

REGISTRAR, GUI: do not allow submit form if req fed attrs are missing