An implementation of the `storagedriver.StorageDriver` interface which uses [Openstack Swift](http://docs.openstack.org/developer/swift/) for object storage.
`container`: The name of your Swift container where you wish to store objects. An additional container - named `<container>_segments` to store the data will be used. The driver will try to create both containers during its initialization.
`tenant`: (optional) Your Openstack tenant name.
`region`: (optional) The name of the Openstack region in which you would like to store objects (for example `fr`).
`chunksize`: (optional) The segment size for Dynamic Large Objects uploads (performed by WriteStream) to swift. The default is 5 MB. You might experience better performance for larger chunk sizes depending on the speed of your connection to Swift.
`rootdirectory`: (optional) The root directory tree in which all registry files will be stored. Defaults to the empty string (container root).
