def new(relation, new_options = EMPTY_HASH)
      self.class.new(relation, new_options.empty? ? options : options.merge(new_options))
    end
def new(relation, new_options = EMPTY_HASH)
      self.class.new(relation, new_options.empty? ? options : options.merge(new_options))
    end
Return a new changeset with provided relation

 New options can be provided too

 @param [Relation] relation
 @param [Hash] new_options

 @return [Changeset]

 @api public