Remove generic Exception when using assertRaises
Remove generic Exception when using assertRaises

This change fixes errors associated with H202 checks and enables H202
checks.

Change-Id: I28a48d1b58f2f1f6824ee4b45782a0c961fe9fb5

openstack/neutron-fwaas,flavio-fernandes/networking-odl,flavio-fernandes/networking-odl,CiscoSystems/networking-odl,gaolichuang/neutron-fwaas,openstack/networking-odl,FedericoRessi/networking-odl,schoksey/networking-odl,schoksey/networking-odl,citrix-openstack-build/neutron-vpnaas,openstack/neutron-vpnaas,dougwig/x-neutron-vpnaas,openstack/networking-odl,CiscoSystems/networking-odl,citrix-openstack-build/neutron-fwaas,FedericoRessi/networking-odl,openstack/neutron-fwaas,dougwig/x-neutron-fwaas,openstack/networking-odl,openstack/neutron-vpnaas,gaolichuang/neutron-fwaas,mestery/x-stackforge-odl