cli: Fix 'status all' xml output when volumes are not started

 Backport of 7d9bc0d21408c31651a65a6ec0e67c3b8acd0fde from master

CLI now only outputs one XML document for 'status all' only containing
those volumes which are started.

BUG: 1004218
Change-Id: I119ac40282380886b46a09fd9a19d35115fd869d
Signed-off-by: Kaushal M <kaushal@redhat.com>
Reviewed-on: http://review.gluster.org/5970
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>