Add language chooser to homepage example

[joeduffy]

It just struck me that our homepage example that we lead with is JS-only, probably reinforcing the (incorrect) perception that we're an overly JS-specific technology.

I'd hope this is offset by the prominent array of language logos in the lower left, however Ii's worth adding a language chooser and having this example available in those variants. @zchase did this for a marketing landing page recently in a way that probably fits more stylistically than the standard chooser.

[susanev]

gonna close this, as that screenshot is outdated, and we have a language chooser on our homepage now.