revise the user concept

[th-schwarz]

• introduce an user
• each user can have one or more hosts, this should be respected at the log view
• the api-token should be removed

[th-schwarz]

@Service
public class CustomUserDetailsService implements UserDetailsService {

    private UserRepository userRepository;

    public CustomUserDetailsService(UserRepository userRepository) {
        this.userRepository = userRepository;
    }

    @Override
    public UserDetails loadUserByUsername(String email) throws UsernameNotFoundException {
        User user = userRepository.findByEmail(email);

        if (user != null) {
            return new org.springframework.security.core.userdetails.User(user.getEmail(),
                    user.getPassword(),
                    mapRolesToAuthorities(user.getRoles()));
        }else{
            throw new UsernameNotFoundException("Invalid username or password.");
        }
    }

    private Collection < ? extends GrantedAuthority> mapRolesToAuthorities(Collection <Role> roles) {
        Collection < ? extends GrantedAuthority> mapRoles = roles.stream()
                .map(role -> new SimpleGrantedAuthority(role.getName()))
                .collect(Collectors.toList());
        return mapRoles;
    }
}