/// <summary>
/// Brise ulogu korisniku
/// </summary>
/// <param name="role">uloga</param>
public virtual void RemoveRole(Role role)
{
roles.Remove(role);
}
/// <summary>
/// Dodaje ulogu korisniku
/// </summary>
/// <param name="role">uloga</param>
public virtual void AddRole(Role role)
{
roles.Add(role);
}