[swift/check_swift_ring_usage] Add critical and warn default values
[swift/check_swift_ring_usage] Add critical and warn default values

magic0704/monitoring-for-openstack,padthaitofuhot/monitoring-for-openstack,magic0704/monitoring-for-openstack,stackforge/monitoring-for-openstack,openstack/monitoring-for-openstack,openstack/monitoring-for-openstack,stackforge/monitoring-for-openstack,tcpcloud/monitoring-for-openstack,tcpcloud/monitoring-for-openstack,padthaitofuhot/monitoring-for-openstack