Improvement #135
+ changed behaviour: target folders are now marked HIDDEN and FORBIDDEN
* fixed error in computation of derived files
Merge branch 'pu/135-delete-maven-target-only-if-clean'
Feature #123 Ability to skip b2 bootstrapper
+ added -DskipB2 and integration test
Merge branch 'pu/123-ability-to-skip-b2-bootstrapper'