Change authtoken to keystoneclient.middleware.auth_token:filter_factory

Add authurl before authtoken in the heat-api pipeline
And change filter:authtoken to:
[filter:authtoken]
paste.filter_factory = keystoneclient.middleware.auth_token:filter_factory

Further information please refer to related bug.

Related-Bug: #1259364

Change-Id: If71772a84f783e7ebe662d7d6338e86d8dcb9812
Merge "Change authtoken to keystoneclient.middleware.auth_token:filter_factory"