perf(languages): improved js caching of languages by using simplecache

fixes #7458

This replaces the ajax language views which booted the engine every view to only report a 304 not modified... this fix replaces this with just a few milliseconds and a normal cacheable .js file if you use tools like Varnish
@ewinslow might have some insight here. Since we're URL sniffing anyway we could cut the notices to 1 by only extending the currently requested language. I'd also be OK with just altering views to handle this use case specifically.