Update Heat element for Havana config changes.

Change-Id: Ic7fcdb4ccf74c77f9b63fa1635feb167a4af7e72
Change Heat instance_user to heat-admin.

Default is 'ec2-user', which is more than a little inappropriate.

Change-Id: I1ea29d1436a74cf365e7a7d70c7f5f9735baf5ca
Make heat services work in boot-stack.

Change-Id: Ieab8df6c7efd6d66a9567fe099b73a4d98a0ba35