Add an option to let the operator choose a proper region_name.
Some operator are not using S3 from amazon but from other provider.
In such case, the get_s3_location cannot give good region_name.
Adding an option from config seems a better option that relying on
hardcoded stuff in the code.
Signed-off-by: Arnaud Morin <arnaud.morin@ovhcloud.com>
Change-Id: I71352e75f6415494709d8fb62c8b13f3ea7c6016
2ad4a73e7f