Convert image URLs in React to require calls

This allows Webpack to insert the proper image URL after builds steps like
adding a hash and so on. The path you supply to `require` is relative to the JS
source file, just like any other would be.

src/components/views/dialogs/ChatCreateOrReuseDialog.js

@@ -127,7 +127,7 @@ export default class ChatCreateOrReuseDialog extends React.Component {
                 onClick={this.props.onNewDMClick}
             >
                 <div className="mx_RoomTile_avatar">
-                    <img src="img/create-big.svg" width="26" height="26" />
+                    <img src={require("../../../../res/img/create-big.svg")} width="26" height="26" />
                 </div>
                 <div className={labelClasses}><i>{ _t("Start new chat") }</i></div>
             </AccessibleButton>;