Update MongoDB_Plugin_template_export.xml

For newer zabbix 2.2.1 versions running on CentOS 6.5. Also zabbix_sender 2.2.1 will fail in case some items don't have values. Fix: use zabbix_sender 2.0.6
Merge pull request #1 from mstuparu/patch-1

Update MongoDB_Plugin_template_export.xml