add i18n middlware

middleware/i18n.js

@@ -0,0 +1,7 @@
+export default function ({ req, app, store }) {
+  if (process.server) {
+    const lang = req.acceptsLanguages('en', 'it')
+    store.commit('setLocale', lang || 'it')  
+    app.i18n.locale = store.state.locale
+  }
+}