class HTMLPipeline::NodeFilter::AssetProxyFilter

Proxy images/assets to another server, such as [cactus/go-camo](github.com/cactus/go-camo#). Reduces mixed content warnings as well as hiding the customer’s IP address when requesting images. Copies the original img ‘src` to `data-canonical-src` then replaces the `src` with a new url to the proxy server.

Based on github.com/gjtorikian/html-pipeline/blob/v2.14.3/lib/html/pipeline/camo_filter.rb