Add address_scope_db to neutron/models/head.py
Add address_scope_db to neutron/models/head.py

The head.py file ensures that all relevant models are
imported when ModelsMigrationSync tests are run in
neutron/tests/functional/db/test_migrations.   This is
one of the models that needs to be present else the
"address_scopes" table comes out as missing.   The
error is usually concealed by the fact that the module
was imported as a side effect of other tests but
is revealed if one runs test_migrations.py alone.

Change-Id: I954d8385c479de663ef1a5ef439866d2d927bcf3

igor-toga/local-snat,mattt416/neutron,wolverineav/neutron,paninetworks/neutron,neoareslinux/neutron,MaximNevrov/neutron,sasukeh/neutron,dims/neutron,sebrandon1/neutron,cloudbase/neutron,silenci/neutron,huntxu/neutron,eayunstack/neutron,wolverineav/neutron,klmitch/neutron,cisco-openstack/neutron,glove747/liberty-neutron,noironetworks/neutron,mmnelemane/neutron,javaos74/neutron,yanheven/neutron,jacknjzhou/neutron,barnsnake351/neutron,vivekanand1101/neutron,swdream/neutron,suneeth51/neutron,SamYaple/neutron,openstack/neutron,shahbazn/neutron,openstack/neutron,vivekanand1101/neutron,skyddv/neutron,bigswitch/neutron,takeshineshiro/neutron,asgard-lab/neutron,suneeth51/neutron,javaos74/neutron,apporc/neutron,cloudbase/neutron,swdream/neutron,dhanunjaya/neutron,watonyweng/neutron,yanheven/neutron,MaximNevrov/neutron,asgard-lab/neutron,bigswitch/neutron,mattt416/neutron,adelina-t/neutron,JianyuWang/neutron,openstack/neutron,jacknjzhou/neutron,dhanunjaya/neutron,igor-toga/local-snat,apporc/neutron,barnsnake351/neutron,huntxu/neutron,mahak/neutron,SamYaple/neutron,sebrandon1/neutron,skyddv/neutron,eayunstack/neutron,mahak/neutron,watonyweng/neutron,silenci/neutron,jumpojoy/neutron,paninetworks/neutron,adelina-t/neutron,chitr/neutron,chitr/neutron,klmitch/neutron,mahak/neutron,cisco-openstack/neutron,sasukeh/neutron,takeshineshiro/neutron,noironetworks/neutron,glove747/liberty-neutron,neoareslinux/neutron,mmnelemane/neutron,jumpojoy/neutron,shahbazn/neutron,JianyuWang/neutron,dims/neutron