Bilingual support

[daiyi]

Button to toggle between English and German.

working demo: http://www.daiyi.co/clojurebridge-berlin.github.io

It defaults to English (I inferred this is an English-first website because the English translation appeared first when reading left-to-right, and also later on in the page the German translations are italicised as if whispered. Let me know if we should do German-first!) if there's no javascript or language preferences set in the browser. I tested it with javascript blockers and it does fine.

You can set the language with url params to test all the settings:
http://www.daiyi.co/clojurebridge-berlin.github.io/?lang=en
http://www.daiyi.co/clojurebridge-berlin.github.io/?lang=de

Both languages at the same time:
http://www.daiyi.co/clojurebridge-berlin.github.io/?lang=all
(Should look almost identical to the existing website)

TODO:

• make language selection buttons

previous discussion: clojurebridge-berlin/organization#164 (comment)