- cleanup code:
 * removed unused repository data from changeset
 * removed unused variables in updateDescription
 * added comments for removed changeset sections
- moved strip section handing into new data structure. The reading of
  the default strip section data has been moved to the
  prepare/createBootImage functions and is no longer part of the KIWIXML
  constructor. The following legacy functions will be removed:

  * removed __getStripDelete_legacy
  * removed __getStripTools_legacy
  * removed __getStripLibs_legacy
  * removed __addStrip_legacy
- Create KIWIXMLDefStripData object:
  * encapsulate the KIWI defined default strip data
  * Use the new object in the ImageCreator to update the
    bootXML description accordingly plus some minor refactoring
    to avoid code duplication for the bootXML update
  * Implement unit tests
- Remove any knowledge of the default strip data from the
  XML class implementations