Fixing composer issue where it doesn't respect check() always disposes

[mkcode]

Chaplin's composer is not respecting the check method and is always disposing regardless. Simply using the check method to determine if a composition is stale or not works great for me.

The long form example here: http://docs.chaplinjs.org/chaplin.composer.html does not work as described before this PR.

[mkcode]

With regard to #779 - I think we would want to use the check method as it was intended rather than introducing new API points. It seems more robust to me than a @share method on the controller - all of the compose properties are available inside the check method to use.

Also - I could not get the mocha tests running on my machine. Tests will follow if this gets some positive feedback.

[paulmillr]

The example is wrong — it should say model.id isnt 42, not is.

Works for me:

i = 0
class cls extends Chaplin.Model
  initialize: ->
    @subscribeEvent 'a', =>
      i += 1
      @set 'a', i

    @reuse 'stuff',
      compose: ->
        console.log 'compose'
        @model = new cls
      check: ->
        console.log 'check', @model.get('a')
        @model.get('a') isnt 3


[Log] compose (app.js, line 250)
[Log] check undefined (app.js, line 254)
> Chaplin.mediator.publish('a', 1)
< Object

[Log] check 1 (app.js, line 254, x3)
> Chaplin.mediator.publish('a', 1)
< Object

[Log] check 2 (app.js, line 254, x3)
> Chaplin.mediator.publish('a', 1)
< Object

[Log] check 3 (app.js, line 254)
[Log] compose (app.js, line 250)