PIMCORE-1945 - Enabling plugin ends with fatal error

git-svn-id: http://www.pimcore.org/svn/pimcore/private/core/trunk@2771 1f8fe7d8-47f0-464c-8d0a-336f4953ab05
PIMCORE-1946 - Update less.js

git-svn-id: http://www.pimcore.org/svn/pimcore/private/core/trunk@2772 1f8fe7d8-47f0-464c-8d0a-336f4953ab05