lib/swift: the s3_token middleware should be provided by keystonemiddleware

Recently, keystoneclient.middleware has been moved from keystoneclient to
keystonemiddleware. The latter should be used.

Change-Id: Ib9489a21b988b32fc17399c08eeb60862efae034
Closes-Bug: #1452315
diff --git a/lib/swift b/lib/swift
index 456dde4..820042d 100644
--- a/lib/swift
+++ b/lib/swift
@@ -439,7 +439,7 @@
     if is_service_enabled swift3; then
         cat <<EOF >>${SWIFT_CONFIG_PROXY_SERVER}
 [filter:s3token]
-paste.filter_factory = keystoneclient.middleware.s3_token:filter_factory
+paste.filter_factory = keystonemiddleware.s3_token:filter_factory
 auth_port = ${KEYSTONE_AUTH_PORT}
 auth_host = ${KEYSTONE_AUTH_HOST}
 auth_protocol = ${KEYSTONE_AUTH_PROTOCOL}