* Consolidate service subscriptions in base class.
* Remove unsynchronized and unneeded cache of subscriptions.
* Do not unregister participant when removing subscription.
* Fix status wrongly set to ONLINE when exception is thrown.
* Refactor error handling for WemoHttpCall.
* Adjust log level for communication errors.
* Add automatic subscription renewal.
* Fix more ONLINE/OFFLINE status transition issues.
* Adjust log level when getWemoURL fails because device is offline.
* Remove redundant logging.
Signed-off-by: Jacob Laursen <jacob-github@vindvejr.dk>