Delete uneeded filter:authN section

keystone.middleware.quantum_auth_token doesn't even exist anymore
The auth_token middleware has beed moved to keystoneclient

Using keystone.middleware.auth_token, which nowadays is just a compatibilty
wrapper for keystoneclient.middleware.auth_token, breaks in setups where
keystone is installed on a different node. Using keystoneclient instead should
work in all cases as it will be pulled in via package dependencies.
Merge pull request #59 from rhafer/pull-req-release-pebbles-master-197808408153b82a03525bc760b96ecadfb330c3

The keystone auth_token middleware has been move to keystoneclient [4/4]