Support for S3 AP South East 2 Sydney

Add support for S3 in the South East 2 Sydney region.

I'm a libcloud newbie but I've copied an existing commit adding an S3 region and created a branch https://github.com/apache/libcloud/commit/6be9fc24cd3f2b8e100b162911b3081bf7d89eaf that works for the very cursory testing I've done (upload and download via CKAN and ckanext-cloudstorage). Let me know what I'd need to do to progress this to a PR.