WebService import: pass idMapper to tag

git-svn-id: http://www.pimcore.org/svn/pimcore/private/core/trunk@2603 1f8fe7d8-47f0-464c-8d0a-336f4953ab05
added check to object/asset/document: an element can't be the parent of itself

git-svn-id: http://www.pimcore.org/svn/pimcore/private/core/trunk@2604 1f8fe7d8-47f0-464c-8d0a-336f4953ab05