title: GCS, only user who logged in can see images in my mosaic
body: <p>I am building a mosaic using Google cloud storage, and I store the user uploaded image in a bucket. However, to see any images, you must log in(a google account) first. I have set the bucket to public and any user who had already logged in can view the image. But I want the images to show up even if they haven't logged in. What should I do?
  I store the url of the image in my database: </p>
  
  <pre class="lang-py prettyprint-override"><code>#this part is the return function of my image upload
  imageurl= 'https://storage.cloud.google.com/fortest098.appspot.com/{}'.format(mosaicLocation)
  
  # and this is how i put my image into the database:
  ImageInfo(...,image_url=imageurl).put
  
  </code></pre>
  
  <p>am I suppose to get a public url or something?</p>