Update ospurge.py file

Added classes to delete below resources. Standard ospurge was not deleting these resources. 

'NeutronFireWall'
'NeutronFireWallPolicy'
'NeutronFireWallRule'
'NeutronLbMembers'
'NeutronLbVip'
'NeutronLbHealthMonitor'
'NeutronLbPool'
'NeutronMeteringLabel'
'NeutronMeteringLabelRule'