Description of problem:
Actually, we can't configure a swift node with multi disks.

Ring is hard configured:

  swift_device:
    description: Swift device formatted for swift-ring-builder
    value:
      str_replace:
        template: 'r1z1-IP:%PORT%/d1' 
 

Version-Release number of selected component (if applicable):
RHEL 7.1 with lastest tripleo-heat-template

How reproducible:
We deploy a standard infrastructure with swift node. 

Actual results:
Only one disk is used. 

Expected results:
We would like to configure other disks (as is done with ceph)