added optional to set authorization header token

Author: jhz

src/components/fetch-wrapper.jsx

@@ -10,7 +10,7 @@ function withFetching(WrappedComponent, props) {
     constructor(props) { // eslint-disable-line no-shadow
       super(props);
       this.state = {};
-      this.xhr = this.createRequest(props.filePath);
+      this.xhr = this.createRequest(props.filePath, props.authToken);
     }
 
     componentDidMount() {
@@ -28,9 +28,12 @@ function withFetching(WrappedComponent, props) {
       this.abort();
     }
 
-    createRequest(path) {
+    createRequest(path, authToken=null) {
       let xhr = new XMLHttpRequest();
 
+      if(authToken !== null)
+        xhr.setRequestHeader('Authorization', authToken);
+
       if ('withCredentials' in xhr) {
         // XHR for Chrome/Firefox/Opera/Safari.
         xhr.open('GET', path, true);

src/components/file-viewer.jsx

@@ -85,6 +85,7 @@ class FileViewer extends Component {
 FileViewer.propTypes = {
   fileType: PropTypes.string.isRequired,
   filePath: PropTypes.string.isRequired,
+  authToken: PropTypes.string,
   onError: PropTypes.func,
   errorComponent: PropTypes.element,
   unsupportedComponent: PropTypes.element,