[v6r12] Fixes for DTCommand and GOCDBClient for the GOCFB service type

there were some bugs to fix, related to:
1. the DownTime command
its 2 methods (doCache and doNew) to monitor the DTs that now take into account correctly the DT severity (Outage vs Warning); and  pick the proper GOCDB service type
2. GODDBClient 
its method downTimeXMLParsing can now handle the "service type" parameter properly and return the correct downtime id (i.e. just the number while before it used to return number + hostname)

is dt['GOCDBServiceType'] always added, even for non Storage Elements?