help message mistype correction
Remove duplicate part from the docs, move JSDoc comment for Npm.require
don't exit on add when only some packages are a noop
Revert default bind IP to 0.0.0.0.

We still use localhost as DDP_DEFAULT_CONNECTION_URL for mobile builds
if another host isn't provided; we just don't want localhost to
overwrite an unspecified host for the proxy to bind to.

Fixes #2596.