Reference keystone URIs rather than building URI

lib/keystone sets KEYSTONE_AUTH_URI and KEYSTONE_SERVICE_URI that
other projects should use rather than building the URL themselves.
This will allow us to more easily drop the port altogether.

Change-Id: I7467aae680215f3045d32a088af2187e1eba8169
diff --git a/lib/swift b/lib/swift
index 8cb94ef..4330e3b 100644
--- a/lib/swift
+++ b/lib/swift
@@ -457,9 +457,7 @@
         cat <<EOF >>${SWIFT_CONFIG_PROXY_SERVER}
 [filter:s3token]
 paste.filter_factory = keystonemiddleware.s3_token:filter_factory
-auth_port = ${KEYSTONE_AUTH_PORT}
-auth_host = ${KEYSTONE_AUTH_HOST}
-auth_protocol = ${KEYSTONE_AUTH_PROTOCOL}
+auth_uri = ${KEYSTONE_AUTH_URI}
 cafile = ${SSL_BUNDLE_FILE}
 admin_user = swift
 admin_tenant_name = ${SERVICE_PROJECT_NAME}