Fix Image URL source cache issue

[vusters]

We cache the image's URL so they can load faster the next time:

Image:
  source: https://example.com/1234

This seems to be a problem if the image has been updated at the URL (e.g. Profile photo changed and uploaded to the server). When we load this page again, the image still points to the old one since it was cached.

Please check:

• check whether the image should be cached? as in if does the Image bust the cache if its http header says it has changed
• If we can't cache the image by the http header, so we need a flag that say cache: false to force the image to be loaded every time?