Add a fix for wrong directory npm permissions.

Completely fresh installs will get ~/tmp and ~/.npm directories which
are owned by root.  This fix prevents that.

Also included are some section headers to better deliniate the parts of
the setup that non-Vagrant users won't be intersted in.
Merge pull request #161 from juju/fix-npm-directory-permissions-for-fresh-builds

Completely fresh installs will get ~/tmp and ~/.npm directories which
are owned by root.  This fix prevents that.

Also included are some section headers to better deliniate the parts of
the setup that non-Vagrant users won't be intersted in.