add parameters for opencontrail version for client

Change-Id: I6f6ddbe50fcb6325a049aa1adbfe270442b46a89
diff --git a/metadata/service/tor/single.yml b/metadata/service/tor/single.yml
index 1f44326..7dc070c 100644
--- a/metadata/service/tor/single.yml
+++ b/metadata/service/tor/single.yml
@@ -6,7 +6,7 @@
     opencontrail_tor_agents: 1
   opencontrail:
     common:
-      version: 2.2
+      version: ${_param:opencontrail_version}
       identity:
         engine: keystone
         host: 127.0.0.1