Convert CommonJS exports to ES6-compatible exports

We use `export default` begrudgingly here. Ideally we'd use just `export`, though this entire SDK expects things to be exported as a default. Instead of breaking everything, we'll sacrifice our export pattern for a smaller diff - a later commit can always do the default export -> regular export conversion.

src/components/views/create_room/CreateRoomButton.js

@@ -1,5 +1,6 @@
 /*
 Copyright 2015, 2016 OpenMarket Ltd
+Copyright 2019 The Matrix.org Foundation C.I.C.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -19,7 +20,7 @@ import PropTypes from 'prop-types';
 import createReactClass from 'create-react-class';
 import { _t } from '../../../languageHandler';
 
-module.exports = createReactClass({
+export default createReactClass({
     displayName: 'CreateRoomButton',
     propTypes: {
         onCreateRoom: PropTypes.func,

src/components/views/create_room/Presets.js

@@ -1,5 +1,6 @@
 /*
 Copyright 2015, 2016 OpenMarket Ltd
+Copyright 2019 The Matrix.org Foundation C.I.C.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -25,7 +26,7 @@ const Presets = {
     Custom: "custom",
 };
 
-module.exports = createReactClass({
+export default createReactClass({
     displayName: 'CreateRoomPresets',
     propTypes: {
         onChange: PropTypes.func,

src/components/views/create_room/RoomAlias.js

@@ -1,5 +1,6 @@
 /*
 Copyright 2015, 2016 OpenMarket Ltd
+Copyright 2019 The Matrix.org Foundation C.I.C.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -19,7 +20,7 @@ import PropTypes from 'prop-types';
 import createReactClass from 'create-react-class';
 import { _t } from '../../../languageHandler';
 
-module.exports = createReactClass({
+export default createReactClass({
     displayName: 'RoomAlias',
     propTypes: {
         // Specifying a homeserver will make magical things happen when you,