Fix hardcoded messages (again)

src/pages/ErrorPage.js

@@ -1,4 +1,5 @@
 import React, { PropTypes } from "react";
+import { FormattedMessage } from "../utils/IntlComponents";
 
 class ErrorPage extends React.Component {
 
@@ -10,7 +11,7 @@ class ErrorPage extends React.Component {
     const { err } = this.props;
     return (
       <div>
-        <h1>Error displaying this page</h1>
+        <h1><FormattedMessage message="meta.errorTitle" /></h1>
 
         { process.env.NODE_ENV === "development" && err &&
           <pre align="center">

src/pages/NotFoundPage.js

@@ -6,7 +6,7 @@ class NotFoundPage extends React.Component {
   render() {
     return (
       <div>
-        <FormattedMessage message="meta.notFoundTitle" />
+        <h1><FormattedMessage message="meta.notFoundTitle" /></h1>
       </div>
     );
   }