Feature/langloc

This will return a client.json file based on user preference.
It will work from most preferred to least, to "en" as the default.
It also presumes all pathnames are in lower case (because LCD)

@kitcambridge, @nchapman r?
Sure does! Go's regular expressions can [operate on large inputs](http://swtch.com/~rsc/regexp/regexp1.html) in linear time, but tend to be [slow](http://benchmarksgame.alioth.debian.org/u64q/performance.php?test=regexdna) for simpler cases. Makes sense to use one if it's more readable, though.