Add switch language button on footer

client/src/components/Header/index.js

@@ -2,7 +2,7 @@ import React, { Component } from 'react';
 import { Link } from 'react-router-dom';
 import PropTypes from 'prop-types';
 import classnames from 'classnames';
-import { Trans } from 'react-i18next';
+import { Trans, withNamespaces } from 'react-i18next';
 
 import Menu from './Menu';
 import Version from './Version';
@@ -73,4 +73,4 @@ Header.propTypes = {
     location: PropTypes.object,
 };
 
-export default Header;
+export default withNamespaces()(Header);