Swauth Support (#65)

* Swauth Support

Swauth is an internal authentication system for Swift. This commit adds
support for Swauth in a way that still enables the resulting
*gophercloud.ServiceClient to still be able to use the existing ObjectStorage
API calls.

* Swauth updates for consistency

* Marking required fields for Swauth
diff --git a/openstack/objectstorage/v1/swauth/testing/doc.go b/openstack/objectstorage/v1/swauth/testing/doc.go
new file mode 100644
index 0000000..7603f83
--- /dev/null
+++ b/openstack/objectstorage/v1/swauth/testing/doc.go
@@ -0,0 +1 @@
+package testing