Authorization logic moved from ApplianceCreator into cancan

Inside `Atmosphere::ApplianceCreator` logic responsible for create authorization occurs. It was moved into cancan ability. 

Fixes redmine 3207 issue.

/cc @nowakowski, @djchrap, @Nuanda - please take a look. Deployed into `dev` - please test.
Okay, then the GUI is misleading because it says "Visibility: with_developer_role" (btw., kind of an awkward way to put it...) while it should say "Availability: development mode only" (or similar).

"Service is only visible to developers" is not the same as "Service is only available in development mode"; here we're testing for the latter - which is okay, but the GUI should probably be adjusted. We need to discuss this with DH.