fix issue with swauth-clean-token returning 403 errors

The issue was due to missing a necessary change that was made when changing
the auth account name from .auth to metadata volume.

the auth account has a group of the same name, so the .auth account
also had a .auth group, so we needed to change that too to the
metadata volume (e.g., gsmetadata)

Change-Id: Iaa3b7a1b2628f5b863807932e863593be0011a82
Signed-off-by: Thiago da Silva <thiago@redhat.com>
Reviewed-on: http://review.gluster.org/6416
Reviewed-by: Luis Pabon <lpabon@redhat.com>
Tested-by: Luis Pabon <lpabon@redhat.com>