web-component-fetch

To use:

npm install -g web-component-fetch
web-component-fetch \
    Polymer/paper-button#0.8-addmain \
    Polymer/font-roboto#bowerjson \
    Polymer/core-icons#0.8-bowermain

Now polymers.html has everything you need to deploy a website to production with paper-button, font-roboto, and core-icons