Download vendor cdn files for gateway

This change set downloads the CDN resources for the gateway
and bundles them with the other static resources for the UI.

This is needed for situations where a user does not have access
to the CDN either because of firewall rules or network policy.

The files and versions remain the same, only now loaded locally
with directory paths matching the CDN paths.

Signed-off-by: Burton Rheutan <rheutan7@gmail.com>