* Support retrieving private device types [Thodoris Greasidis]
* Clear the device type caches when the user changes [Thodoris Greasidis]
* Use the same auth instance in all modules of the sdk instance [Thodoris Greasidis]
* Models/application: Drop unused auth module import [Thodoris Greasidis]
* Unify the caching for all device type endpoints [Thodoris Greasidis]