i18n / build: switch to dist .json file for version "stuff"

[snostorm]

https://iojs.org/dist/index.json provides us with a lot of what is needed to "fill in the blanks" with version numbers, downloads, etc. across the site.

Eventually it'll also help us make a historic versions type page.

Benefits integration with nodejs/build#58 as well.

[snostorm]

• A part of Ongoing build / template process improvements #264
• Waiting for #264 build process - adds various i18n helpers, html-based templates #276

[snostorm]

PR #287 builds on the other PR to add a Releases page (and bring in the latest version throughout the as needed from the same source.)

[snostorm]

Think this is done