Discovery fixes: CPU family and DiscoveryWarnings lacking `ip`

* IBM BladeCenter discovery: include discovered IP address in DiscoveryWarnings 
* Select a single CPU family with lshw. If none found, skip updating CPU information.
* IBM BladeCenter and HP ILO discovery: bail if the CPU family is not known. This will generate exceptions. After checking which families generate problems, the fix should be in
discovery/hp_ilo.py to simply not yield these incomplete processors for further
storage.
* some PEP 8 here and there