Share HTML templates, resources for localized getting started projects

[jasonsanjose]

Since pull #5776 adds a build step to the www repo, we have enough pieces in place to templatize the getting started content so that we don't have duplicate CSS files, images and boilerplate HTML across all localized copies of the project.

I'm guessing that @larz0 would have loved to see this for #6055.

[njx]

Reviewed. Low pri to @jasonsanjose, feel free to reassign.