Fix issue where cookbook upload throws Errno::EACCES (Permission denied @ dir_s_mkdir - /opt/supermarket/embedded/service/supermarket/public/system)
Define a data_directory attribute and use that instead, so it can be overridden
Use the user/group attributes instead of hardcoding
Merge pull request #8 from opscode/irving/fix_system_dir

Fix issue where cookbooks cannot be uploaded