creating the same superuser twice create inconsistent state in accounts about pulsar-manager

[maranmaran]

@coreybutler @fvigotti #564 should solve this

[fvigotti]

in UsersController
there is this check on already exists user :

    @RequestMapping(value = "/users/user", method = RequestMethod.PUT)
...
 Optional<UserInfoEntity> optionalUserEntity =  usersRepository.findByUserName(userInfoEntity.getName());
        if (optionalUserEntity.isPresent()) {
            result.put("error", "User already exist, please check");
            return ResponseEntity.ok(result);
        }

which is missing in this endpoint :

    @RequestMapping(value = "/users/superuser", method = RequestMethod.PUT)

[coreybutler]

I ran into this on 0.3.0