Feature: add models on update callbacks

[syphax-bouazzouni]

Requirement

This PR adds the possibility to add an onUpdate callback to a model attribute

For example

  attribute :name, enforce: [:string, :existence]
  attribute :first_name, onUpdate: :update_name
  attribute :last_name, onUpdate: :update_name

  def update_name(inst, attr)
    self.name = self.first_name + self.last_name
  end

Will ensure that each time we update firt_name or last_name we call the method update_name and make that name will always be firt_name + last_name

Changes

• add onUpdate callback tests

• implement enforce_callback to run an attribute callback

• move the attribute default callback to the save method

• implement onUpdate DSL in the resource settings

• call the attributes onUpdate callback in the save method

[syphax-bouazzouni]

replaced by https://github.com/ncbo/goo/pull/151