Add support to optionally launch the heat service.

This allows the heat service to be started as a devstack service.

Heat is disabled by default, and can be enabled with this in your localrc:
ENABLED_SERVICES+=,heat

There is now a repo of heat-enabled images here:
https://github.com/heat-api/prebuilt-jeos-images/downloads

These can be added to the IMAGE_URLS in your localrc.

After devstack is launched, a template can be invoked with:
nova keypair-add --pub_key $HOME/.ssh/id_rsa.pub heat_key
heat -d create wordpress \
--template-file=../heat/templates/WordPress_Single_Instance.template \
--parameters="InstanceType=m1.tiny;DBUsername=wpuser;DBPassword=wppassword;\
KeyName=heat_key;LinuxDistribution=F16"

Change-Id: I07591295eb2b9eb7868b1577dd3c24b19812a689
diff --git a/stackrc b/stackrc
index cd70284..d8d1008 100644
--- a/stackrc
+++ b/stackrc
@@ -95,6 +95,10 @@
 TEMPEST_REPO=${GIT_BASE}/openstack/tempest.git
 TEMPEST_BRANCH=master
 
+# heat service
+HEAT_REPO=${GIT_BASE}/heat-api/heat.git
+HEAT_BRANCH=master
+
 # Nova hypervisor configuration.  We default to libvirt with **kvm** but will
 # drop back to **qemu** if we are unable to load the kvm module.  ``stack.sh`` can
 # also install an **LXC** or **OpenVZ** based system.