1401: Cannot assign a role with no rights

If someone will try to assign a role with no rights to a user he/she will get an error message:

{
  "timestamp": 1479714389035,
  "status": 500,
  "error": "Internal Server Error",
  "exception": "java.util.NoSuchElementException",
  "message": "No message available",
  "path": "/api/users"
}

There should more appropriate message like: 'the role <<role_name>> cannot be assigned because it has no rights' or we should handle a situation in which the given role has no rights.

Acceptance:

• assigning a role to a user when the role has no rights will not result in a 500
• error message is better
• demo data has no roles without rights