pass locale as key to IntlProvider to force a rerender on locale change

See docs: https://github.com/yahoo/react-intl/wiki/Components#dynamic-language-selection

packages/vulcan-core/lib/modules/components/App.jsx

@@ -85,6 +85,7 @@ class App extends PureComponent {
     return (
       <IntlProvider
         locale={this.getLocale()}
+        key={this.getLocale()}
         messages={Strings[this.getLocale()]}
       >
         <div className={`locale-${this.getLocale()}`}>