Restore heat.db.sync and add Deprecated message.
Restore heat.db.sync and add Deprecated message.

This unpythonic deprecation method is used because this module was only
ever meant to be used from the CLI as 'python -m heat.db.sync'. The
module should be removable in Havana+1.

Fixes bug #1185220

Change-Id: I9943e5c35d9578f899fae1d11b818a2a5a9167c0

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