Bug 49340 Language code for Norwegian bokmål

Just reported https://bugzilla.wikimedia.org/show_bug.cgi?id=49340, but then had a look at the source code and found the language map. 

Seems to work fine. I would preferred to have the map the other way around, but I guess it can be practical since the wiki is located at no.wikipedia.org, not nb.wikipedia.org for historical reasons.