Use basic image viewer

src/models/DirectoryModel.js

@@ -33,6 +33,9 @@ export function createDirectoryModel(origin, accessToken, appId) {
 
       const text = await result.text();
       return text;
+    },
+    getFileUrl(path) {
+      return `${origin}/api/v1/apps/${appId}/files/${path}?access_token=${accessToken}`;
     }
   };
 }