Swift: Stub out Space, add fields, helpers

refs #6938

Add Swift Space with all functions stubbed out.  Add dependencies; remove
explicit six dependency, since it's required by several packages already,
and upgrade bagit so it uses the same version of six as the swiftclient
packages.
Swift: Add move from SS

refs #6938

Problems with VCR.py recording responses for move_from. Update create local
directory to handle paths without any directories.
Swift: Add move to SS

refs #6938
Swift: Add delete path

refs #6938
Swift: Add browse

refs #6938