Vmware Driver, need clean this error info relate to opaqueNetwork

[Fan Guo]

With vCenter version bellow 5.5 always get error info from nova.log
As opaqueNetwork is added since vSphere API 5.5, using API with low version will meet this error.

log from nova.conf, VMwareVCDriver in use----------
2014-08-07 06:34:12.841 25266 ERROR suds.client [req-2b1836fb-a3fd-442f-b999-81ff42692a40 ] <?xml version="1.0" encoding="UTF-8"?>
<SOAP-ENV:Envelope xmlns:ns0="urn:vim25" xmlns:ns1="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
   <ns1:Body>
      <ns0:RetrievePropertiesEx>
         <ns0:_this type="PropertyCollector">propertyCollector</ns0:_this>
         <ns0:specSet>
            <ns0:propSet>
               <ns0:type>HostSystem</ns0:type>
               <ns0:all>false</ns0:all>
               <ns0:pathSet>config.network.opaqueNetwork</ns0:pathSet>
            </ns0:propSet>
            <ns0:objectSet>
               <ns0:obj type="HostSystem">host-410</ns0:obj>
               <ns0:skip>false</ns0:skip>
            </ns0:objectSet>
         </ns0:specSet>
         <ns0:options>
            <ns0:maxObjects>100</ns0:maxObjects>
         </ns0:options>
      </ns0:RetrievePropertiesEx>
   </ns1:Body>
</SOAP-ENV:Envelope>
-----------------------------------------------------------------

[Gary Kotton (garyk)]

This patch should address this issue - https://review.openstack.org/#/c/110477/