PIMCORE-2088 - Escape document root in preg_replace in Asset_Document

git-svn-id: http://www.pimcore.org/svn/pimcore/private/core/trunk@3828 1f8fe7d8-47f0-464c-8d0a-336f4953ab05
build auto version (2942) ...

git-svn-id: http://www.pimcore.org/svn/pimcore/private/core/trunk@3829 1f8fe7d8-47f0-464c-8d0a-336f4953ab05