[Review] Request from 'schubi2' @ 'yast/yast-pkg-bindings/review_140924_flag_onsystem_by_user'

Please review the following changes:
  * 79f724d packaging
  * e3fecfa fixed PkgPropertiesAll
  * c2cb73d moved onSystemByUser to Package.cc
  * 6e7643d fixed name
  * 484da0f taking item pointer
  * 0468414 added onsystem_by_user flag

Please add this (and the other missing properties) to the documentation which is at `PkgProperties`.