Fastly in front of registry.npmjs.org removes need for custom CA

According to http://blog.npmjs.org/ - the implementation of Fastly out the front has moved `registry.npmjs.org` from a custom CA to a standard CA that should be in most curl CA bundles.

At present `install.sh` is broken (curl fails) - but I understand if you would prefer to pin to the new CA rather than removing the custom CA code.