title: i18n.changeLanguage send part of string to locize, not nn-NO, but only nn
body: <p>I'm using locize.io and i18n for translation of my application. Everything was working just fine, but since I added new language with dash: "nn-NO", I'm getting empty {}.</p>
  
  <p>I'm changing language like this: i18n.changeLanguage("nn-NO"), but method sends to server not full string somehow:</p>
  
  <p>Request URL:<a href="https://api.locize.io/KEY_HERE/latest/nn" rel="nofollow noreferrer">https://api.locize.io/KEY_HERE/latest/nn</a>
  Request Method:GET</p>
  
  <p>And when I manually tried with console and cUrl update this request with "nn-NO", I got all translated sentances for "nn-NO" language. </p>
  
  <p>It looks like changeLanguage method doesn't support "-" and cut this string, taking to account only first part of it.</p>
  
  <p>Maybe somebody had this problem? </p>