xenapi: Fix xmlrpclib marshalling error
xenapi: Fix xmlrpclib marshalling error

Fix an error that occurs when trying to marshal an
oslo_i18n._message.Message object via xmlrpclib.

xmlrpclib is not designed to marshal custom objects.  Since
nova_version is only used for this one purpose, don't internationalize
it.

Closes-Bug: 1572264

Change-Id: I04c59993125834fc50abd0c5b6dc3fd0269b7243

vmturbo/nova,cloudbase/nova,rajalokan/nova,mikalstill/nova,rahulunair/nova,phenoxim/nova,rajalokan/nova,openstack/nova,openstack/nova,phenoxim/nova,hanlind/nova,openstack/nova,vmturbo/nova,jianghuaw/nova,jianghuaw/nova,mahak/nova,rahulunair/nova,klmitch/nova,jianghuaw/nova,mahak/nova,bigswitch/nova,gooddata/openstack-nova,alaski/nova,cloudbase/nova,bigswitch/nova,sebrandon1/nova,klmitch/nova,vmturbo/nova,gooddata/openstack-nova,mikalstill/nova,alaski/nova,Juniper/nova,Juniper/nova,rahulunair/nova,Juniper/nova,sebrandon1/nova,sebrandon1/nova,mikalstill/nova,gooddata/openstack-nova,klmitch/nova,rajalokan/nova,mahak/nova,vmturbo/nova,jianghuaw/nova,Juniper/nova,hanlind/nova,rajalokan/nova,hanlind/nova,cloudbase/nova,gooddata/openstack-nova,klmitch/nova