Addition of older Living Connect Z Thermostat to products.xml and protection from null SetpointType

Before adding the older model of the Living Connect Z Thermostat to the products database I was experiencing a null pointer exception due to a null SetpointType in the setpointTypes HashSet.  This is discussed in issue: openhab#796 

In addition to adding the older thermostat this pull request adds protection against null setpointTypes and a log message to help further analysis.

Perhaps you would have preferred these as separate pull requests?  I'm still getting to grips with git.  Hope this helps.