Use BCD's release dates

[foolip]

https://github.com/GoogleChromeLabs/confluence/blob/master/data/version_history.json has release information that's also in https://github.com/mdn/browser-compat-data/tree/master/browsers.

I'd like to use BCD, since that's already being maintained.

This could also help resolve https://github.com/GoogleChromeLabs/confluence/issues/262.