Create a wsgi factory method for Debug filter.
Create a wsgi factory method for Debug filter.

This can be enabled by putting the following in the *-paste.ini
file:
[filter:debug]
paste.filter_factory = heat.common.wsgi:filter_factory
heat.filter_factory = heat.common.wsgi:debug_filter

and adding 'debug' to the pipeline.

This assisted with bug #1133792

Change-Id: I4c2d3194ac9673d095b4115d4b6f385fd2f4fa4e

citrix-openstack-build/heat,Triv90/Heat,varunarya10/heat,cwolferh/heat-scratch,srznew/heat,pratikmallya/heat,dragorosson/heat,redhat-openstack/heat,cryptickp/heat,pshchelo/heat,redhat-openstack/heat,dragorosson/heat,steveb/heat,dims/heat,miguelgrinberg/heat,pshchelo/heat,takeshineshiro/heat,cryptickp/heat,rh-s/heat,ntt-sic/heat,noironetworks/heat,steveb/heat,JioCloud/heat,maestro-hybrid-cloud/heat,jasondunsmore/heat,rdo-management/heat,gonzolino/heat,openstack/heat,rickerc/heat_audit,openstack/heat,Triv90/Heat,rickerc/heat_audit,srznew/heat,NeCTAR-RC/heat,dims/heat,miguelgrinberg/heat,gonzolino/heat,pratikmallya/heat,Triv90/Heat,JioCloud/heat,varunarya10/heat,NeCTAR-RC/heat,takeshineshiro/heat,cwolferh/heat-scratch,noironetworks/heat,rh-s/heat,jasondunsmore/heat,rdo-management/heat,maestro-hybrid-cloud/heat,ntt-sic/heat,citrix-openstack-build/heat