Added AWS_PRELOAD_METADATA options for S3BotoStorage backend to preload bucket metadata.
Added AWS_PRELOAD_METADATA options for S3BotoStorage backend to preload bucket metadata.

cbrepo/django-storages,chalkchisel/django-storages,cbrepo/django-storages,multiplay/django-storages,multiplay/django-storages,chalkchisel/django-storages