the only sql servers I have access to are using the default
`MSSQLSERVER` instance names. I was contacted by someone using a
different instance name and it was failing.
Found 2 bugs in the code:
1) I was returning the default `MSSQLSERVER` as an instance even if it wasn't found in the registry
2) learned that the WMI class naming scheme for non-default instances
was not what I had coded. Changed to incorproate new knowledge.
c868c00e89