isValid() is not available in PostgreSQL driver.
Merge pull request #34 from tauceti2/extSourceSQLFix

isValid() is not available in PostgreSQL driver.
Core: Fixed set method in UF:V:shell module.

Set method calls itself in old behavior, so it causes stack overflow.
In new version this method calls set on UF:D:shell attribute.
Core: fixed behavior of module UF:D:shell

UF:D:shell can be null now because shells are selected primary by
U:D:preferredShells. UD:F:shells is used for forcing one shell on
selected facility for the user. For the same reason fill method is no
longer required (and wanted) for UF:D:shell.
Merge pull request #36 from licehammer/shellsModules

Core: Merge fixes in shells modules
Core: FacilityManager.addAdmin edited, so as it throws right exception (AlreadyAdminException) instead of InternalErrorException, when one user is added more than once as admin.

The functionality is tested with the new written test addAdminWithTwoSameUsers in the FacilityManagerEntryIntegrationTest.