Remove duplicate _version_ definition from askbot's Chinese solr schema

The duplicated _version_ definition in the template prevented
the proper query of Chinese indexed content from Solr.

After the patch had been applied restart Solr and
reindex Chinese content:
sudo service jetty restart
cd /srv/askbot-sites/slot0/config
sudo python manage.py askbot_rebuild_index -l zh

Change-Id: Iaeabc73febc64c45996425225d3ee38db7f36f72

modules/openstack_project/templates/askbot/schema.cn.xml.erb

@@ -163,9 +163,6 @@
 
     <field name="title" type="text_en" indexed="true" stored="true" multiValued="false" />
 
-    <!-- required by solr 4 -->
-    <field name="_version_" type="long" indexed="true" stored="true"/>
-
   </fields>
 
   <!-- field to use to determine and enforce document uniqueness. -->