Fixes #4657: Removes Katello current user setting and moves consumer
authentication checking to the proxies controller.

Previously, the API controller was attempting to handle authentication for
standard users and consumers across all controllers. After moving all consumer
routes and functionality to the Candlepin proxies controller, client authentication
should be handled within the context of that controller and authentication/authorization
controller relegated to the underlying Foreman framework.
Merge pull request #3832 from ehelms/fixes-4657

Fixes 4657: Removes Katello current user setting and moves consumer