Fixes #6211,BZ1102521 - Requiring a user to ping pulp_auth

It looks like the code didn't properly set User.current so Katello.pulp_server
was nil. This code checks for a user in the controller. Also, it handles the
case of no user by skipping the pulp_auth check which needs remote_id from a
user.
Merge pull request #4265 from daviddavis/temp/20140613091921

Fixes #6211,BZ1102521 - Use hidden user's remote id to ping pulp_auth