- move all the driver handling in the XML from the old
  data model to the new data model
  * remove addDrivers_legacy
  * remove getDriversNodeList_legacy
  * remove the driversNodeList class member
- add unit test for syncMBR attribute
- implement ImageBuilder for tar archives (KIWITarArchiveBuilder)
  + remove createImageTar from KIWIImage class
  + update the Factory to return the new builder type
  + update ImageCreator
  + update triggers
  + implement new unit tests
- fixed changelog build helper to correctly indent sub
  entries starting with a '+' or '*' prefix
- run XML validator on the code