HOTFIX: AWS S3 resource returned unsigned if 'public' in bucket name…

…and no credentials on Alyx

Steps for release:

[x] Remove the Access key ID and Secret access key keys from the JSON fields of aws repos on OpenAlyx
[x] Modify the OpenAlyx release script so that the credentials are removed, rather than replaced

NB: The region_name key may remain in the JSON field and the bucket_name must remain.

int-brain-lab / ONE