FetchHelper refactoring: Use the PartQuery from ItemRetriever in fetchhelper.
FetchHelper refactoring: Use the PartQuery from ItemRetriever in fetchhelper.

svn path=/branches/work/akonadi-sqlite/; revision=1106281

kolab-groupware/akonadi,kolab-groupware/akonadi,kolab-groupware/akonadi,kolab-groupware/akonadi