completed step 2 of refactoring task scanner related code
- adapted all task scanner tests to new configuration concept (successfully retested)
- added set methods for build status threshold controls to AbstractCodeStylePluginBuildSettings
- introduced exists method to Control object which tries to resolve the object and returns false if the element was not found (NoSuchElementException)
- modified ensureAdvancedClicked as the old implementation did not work in case the job configuration was opened again (the boolean was never reset).
- bugfix to editJob method