heat add HEAT_DEFERRED_AUTH option
heat add HEAT_DEFERRED_AUTH option

Adds a HEAT_DEFERRED_AUTH, defaulted to trusts, so users can
by default take advantage of the heat trusts functionality
which provides the following benefits:
- Deferred operations (e.g autoscaling) work with token-only auth
- The password field in the heat page of horizon can be made optional
  (horizon patch pending)
- It's more secure because heat no longers stores username/password
  credentials in the DB, only a trust ID.

The previous behavior can be obtained by setting HEAT_DEFERRED_AUTH
to something other than "trusts" - the value will only be set in
the heat.conf if the value of "trusts" is found, otherwise the
heat.conf default will be used (currently "password" which doesn't
use trusts)

Change-Id: I549f1e0071a082ac5d07d0f99db633f8337f3d87
Related-Bug: #1286157

CloudServer/devstack,noironetworks/devstack,kplus/devstack-moonshot,Mahito/devstack,virtualopensystems/devstack,neerja28/Devstack_GlusterFS,atulpatil301/devstack,prithivm/branch01,mc2014/devstack,bigswitch/devstack,BSJAIN92/OpenStack,mmasaki/devstack,affo/devstack,openstack-dev/devstack,richliu/devstack,HPCHub/devstack,samgoon/devstack,ozamiatin/devstack,promptworks/devstack,olivierlemasle/devstack,herrsechs/devstack,sequenceiq/devstack,group-policy/devstack,prithivm/branch01,ozamiatin/devstack,noironetworks/devstack,vsham20/devstack,wenhuizhang/devstack,openstack-dev/devstack,j4/devstack,neerja28/Devstack_GlusterFS,LoHChina/devstack,mc2014/devstack,bigswitch/devstack,dtroyer/devstack,vishnugonela/devstack,HPCHub/devstack,Mahito/devstack,CloudServer/devstack,group-policy/devstack,bswartz/devstack,olivierlemasle/devstack,tianweizhang/devstack,thomasem/devstack,vsham20/devstack,dtroyer/devstack,mmasaki/devstack,liuquansheng47/devstack,wenhuizhang/devstack,nawawi/openstack,eharney/devstack,TwinkleChawla/devstack,liuquansheng47/devstack,bq-xiao/devstack,pacinete/devstack,pacinete/devstack,costingalan/devstack,mssumanth/devstack,samgoon/devstack,BSJAIN92/OpenStack,nawawi/openstack,upadhyay-prashant/devstack,pczerkas/devstack,varunarya10/devstack,affo/devstack,nuxeh/devstack,innodee/openstackk,TwinkleChawla/devstack,parul24/devstack,sc68cal/devstack,thomasem/devstack,vishnugonela/devstack,sc68cal/devstack,varunarya10/devstack,eharney/devstack,kplus/devstack-moonshot,nuxeh/devstack,avvocatodemarchis/devstack,bq-xiao/devstack,eshnil2000/devstack,tianweizhang/devstack,williamthegrey/devstack,dirkmueller/devstack,flavio-fernandes/devstack,herrsechs/devstack,bljgaurav/openstack-test,promptworks/devstack,sequenceiq/devstack,dirkmueller/devstack,costingalan/devstack,pczerkas/devstack,andrewrothstein/devstack,rushiagr/devstack,LoHChina/devstack,parul24/devstack,NaokiMiyata/devstack,andrewrothstein/devstack,upadhyay-prashant/devstack,JioCloud/devstack,bswartz/devstack,pombredanne/devstack,NaokiMiyata/devstack,avvocatodemarchis/devstack,bljgaurav/openstack-test,mssumanth/devstack,rushiagr/devstack,richliu/devstack,atulpatil301/devstack,Juniper/devstack,srics/devstack,j4/devstack,jamielennox/devstack,flavio-fernandes/devstack,pombredanne/devstack