Set swift3 before s3token in proxy server middleware pipeline

swift3 and s3token middlewares were not set in correct order in
/etc/swift/proxy-server.conf when the swift3 service is enabled
with keystone. swift3 must be set before s3token.

Fixes: bug #1166123
Change-Id: I97c051af95cbdc26ccfe9753c5719394e1875dde
diff --git a/lib/swift b/lib/swift
index eb57477..ca9c373 100644
--- a/lib/swift
+++ b/lib/swift
@@ -169,7 +169,7 @@
     # configured keystone it will configure swift with it.
     if is_service_enabled key;then
         if is_service_enabled swift3;then
-            swift_pipeline=" s3token swift3 "
+            swift_pipeline=" swift3 s3token "
         fi
         swift_pipeline+=" authtoken keystoneauth "
     else