This change adds the keystonemiddleware audit paste filter[0]
and enables it for the heat-api, heat-cfn, and heat-cloudwatch
services. This provides the ability to audit API requests
for heat.
[0] https://docs.openstack.org/keystonemiddleware/latest/audit.html
Change-Id: Ib5a7dfd882416553ff6f43aa009e3e67871d7f4c