title: Locale fallback from country to language without having to define each individually
body: <p>I am localizing an app with the default rails I18n with globalize3 as the back-end.</p>
  
  <p>Is it possible to set a locale with a country code (ie <code>:fr-CA</code>) to fallback to its specific language (<code>:fr</code>) before going to the default fallback automatically? I know its possible to set each locale/country manually with </p>
  
  <pre><code>config.i18n.fallbacks = {'fr-CA' =&gt; 'fr'}
  </code></pre>
  
  <p>But it would be nice to not have to add each fallback manually and have this behaviour automatic.</p>