Support x-openstack-request-id for Heat

This patch aims to support "x-openstack-request-id" for Heat.

Nova, Cinder and Neutron have realized "x-openstack-request-id" functionality
by using oslo-incubator.middleware. This functionality will enable effective
log tracing between Heat and Heat caller.

Change-Id: Ida2f3d33b02557c2117aade27ccac7d9351886c9
Closes-bug: #1324065
Merge "Support x-openstack-request-id for Heat"