Ensure contents of install dir are owned by root

/cc @irvingpop @lamont-granquist @opscode/engineering-leads @pburkholder 

This change will be cherry-picked into release/chefdk-0.2.2 also.

Right, but a low privileged process (not our installation process) that's sitting on the box waiting for directories to come in to existence with weak permissions could gain unauthorized access to this directory while we're in the middle of installation. The question is whether they can make anything bad happen by gaining control until we chown it. I'm not clear enough on Unix permissions to understand what that gets you.

If we created the directory with the correct permissions in the first place, there would be no time window...