Fix Avatar upload policy

[YannHulot]

create policy "Anyone can upload an avatar."
  on storage.objects for insert
  with check ( bucket_id = 'avatars' );

I dont think you should allow anyone to upload files to your bucket. That could leave the door open for unwanted uploads in the bucket.
Check that the users has an ID before the upload is done.

[Etheonor]

Should be fixed with 598fd26

[YannHulot]

Nice. Feel free to close this issue.