Update CHANGES.
Include server side error message in the multipart error exception.
Fix generic OpenStack Swift driver and don't ignore ex_force_service_type
and ex_force_service_name argument provided by the user.
Deprecate "CLOUDFILES_SWIFT" provider constant in favor of "OPENSTACK_SWIFT".

Also rename driver and connection classes: CloudFilesSwiftStorageDriver ->
OpenStackSwiftStorageDriver, CloudFilesSwiftConnection ->
OpenStackSwiftConnection.
docs: Add some documentation and examples for OpenStack Swift driver.
Update contrib script to ignore some deprecated provider constants.
Re-generate documentation fixtures.
docs: Reword some stuff.