That's fine with me.

Tho separate `serveLanguageSelectPage` in two:
* One that looks if a `lang` value was in the query.
* One that does the serve if it was.

``` go
lang, ok := extractLangSelection(req.URL.RawQuery)  // Helper func here, returns (string, bool)
if !ok {
    b.answerWithLangSelection(rw)  // Func send to selection page
    return
}
posts = b.postMngr.GetAllPostsWithLanguage(lang)
```