Fix quota usage tracker for security group rules
Fix quota usage tracker for security group rules

This simple patch ensures usage for security group rules is
marked as dirty when a security group rule is deleted.
To this aim, the security group rule is deleted using ORM
in order to ensure the sqlalchemy even if fired.

Closes-Bug: #1499339

Change-Id: I1e81fe03fed14ec438cea5d7675f66caeb91afd8

mahak/neutron,wolverineav/neutron,huntxu/neutron,asgard-lab/neutron,jumpojoy/neutron,dims/neutron,huntxu/neutron,openstack/neutron,openstack/neutron,chitr/neutron,mahak/neutron,wolverineav/neutron,dhanunjaya/neutron,yanheven/neutron,eayunstack/neutron,eayunstack/neutron,igor-toga/local-snat,glove747/liberty-neutron,apporc/neutron,SamYaple/neutron,klmitch/neutron,MaximNevrov/neutron,swdream/neutron,sebrandon1/neutron,jumpojoy/neutron,SamYaple/neutron,igor-toga/local-snat,bigswitch/neutron,dims/neutron,bigswitch/neutron,noironetworks/neutron,yanheven/neutron,cloudbase/neutron,sebrandon1/neutron,glove747/liberty-neutron,noironetworks/neutron,mahak/neutron,cloudbase/neutron,klmitch/neutron,swdream/neutron,asgard-lab/neutron,openstack/neutron,chitr/neutron,apporc/neutron,dhanunjaya/neutron,MaximNevrov/neutron