Added short doc about new Heat engine
Added short doc about new Heat engine

* Short overview was added
* Summary table about implemented features added as well

Change-Id: Ia3ff8f56daa0a0646be0b9627b0dd4da667e12cf

redhat-openstack/sahara,citrix-openstack-build/sahara,bigfootproject/sahara,henaras/sahara,keedio/sahara,esikachev/sahara-backup,keedio/sahara,redhat-openstack/sahara,keedio/sahara,crobby/sahara,citrix-openstack-build/sahara,bigfootproject/sahara,henaras/sahara,zhujzhuo/Sahara,mapr/sahara,crobby/sahara,esikachev/scenario,citrix-openstack-build/sahara,xme1226/sahara,openstack/sahara,esikachev/scenario,redhat-openstack/sahara,zhujzhuo/Sahara,tellesnobrega/storm_plugin,zhangjunli177/sahara,xme1226/sahara,bigfootproject/sahara,esikachev/sahara-backup,crobby/sahara,egafford/sahara,xme1226/sahara,ekasitk/sahara,matips/iosr-2015,ekasitk/sahara,esikachev/sahara-backup,matips/iosr-2015,tellesnobrega/sahara,zhujzhuo/Sahara,mapr/sahara,tellesnobrega/storm_plugin,henaras/sahara,esikachev/scenario,tellesnobrega/storm_plugin,zhangjunli177/sahara,egafford/sahara,ekasitk/sahara,zhangjunli177/sahara,mapr/sahara,tellesnobrega/sahara,matips/iosr-2015,openstack/sahara