removed unique key from documents, objects and assets table

git-svn-id: http://www.pimcore.org/svn/pimcore/private/core/trunk@2850 1f8fe7d8-47f0-464c-8d0a-336f4953ab05
demo: updated data

git-svn-id: http://www.pimcore.org/svn/pimcore/private/core/trunk@2851 1f8fe7d8-47f0-464c-8d0a-336f4953ab05