Bugfix the swift-ring-builder output scanner

The ring output scanner uses the output of the swift-ring-builder
to determine which disks are new and which have already been added
to the swift ring.  The output is slightly different in grizzly
and thus the new format needed to be handled here.

Fixes LP#1240634

Change-Id: I6788da8746d9572777b025722c3a9e74fdb946a1