Add example of complex cancel creation action (with "draft" flag filter)

[abratashev]

In continuation of #74, for more complex situations, creation of entity is splitted on a few views with child widgets.
For that cases we can't use "cancel-create", because BcStateAware cache currently can't store DTO hierarchy between views.
But we can "hide" non-completed records with implicit filter, for example, with getParentSpecification() method.
We can define "draft" flag that will be "true" throughout the whole creation process, and disable that flag after we complete the record.

For check this concept, we can use "Client" creation views