post-1.9 mega update

- bullet-proof against linkage errors when developing
- demote some log entries from notice/warning to info
- ensure device names are strings
- fix https://github.com/TheThingSystem/steward/issues/255
- update aros driver to use only numeric values for fanSpeed
- update plant drivers to get better placement names
- normalize device types to make things easier for clients
- add ‘display’ property for gauges
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