def set_roles *roles
      roles_to_set = make_valid_roles(*roles).flat_uniq
      return false if !roles_to_set || roles_to_set.empty?
      store.set_roles(roles_to_set) 
    end
def set_roles *roles
      roles_to_set = make_valid_roles(*roles).flat_uniq
      return false if !roles_to_set || roles_to_set.empty?
      store.set_roles(roles_to_set) 
    end
Sets new roles for the subject
 @param [Array<Symbol>] list of role names
 @return [true, false, Error] true if set ok, false if any roles were invalid, Error on some error