Prevent listing huge buckets on S3.
Prevent listing huge buckets on S3.

Previously, in when `AWS_PRELOAD_METADATA` is True,
`S3BotoStorage.entries` would list every file in the bucket. However,
if there is a `location` specified on the storage, we don't use the
whole storage bucket with that storage backend. So pass our `location`
as the `prefix` to the call to `entries`.

taxido/django-storages,un33k/django-storages,jneves/django-storages,chenjyw/django-storages,hobarrera/django-storages,falcon1kr/django-storages,torchbox/django-storages,cherepski/django-storages,faxioman/django-storages,ZuluPro/django-storages,mbarrien/django-storages,richardbx/django-storages,Chris7/django-storages,syapse/django-storages,juiceinc/django-storages,kamotos/django-storages,joshisa/django-storages,jschneier/django-storages,imhome/django-storages-redux,chenjyw/django-storages,mroth23/django-storages,celerityweb/django-storages