MarkerChildModel on doRebuild all disable clonedModel

[nmccready]

See #1442

Overall design changes:

Fix child code do the checks on cloning. Where you might want to make it a function.

marker-child-model

To:

maybeCloneModel: =>
  @clonedModel = _.clone(@model,true) if not @scope.doRebuildAll

Finally use doRebuild all in your implementation markup <markers doRebuildAll="true"></markers>.

[nmccready]

@mlegenhausen