[rdo-list] Adding backwards compatible tripleo-heat-templates packaging

[Mike Burns]

I've posted a WIP patch[1] based on what we've done in the downstream
OSP releases with tripleo-heat-templates to provide backwards
compatible heat templates for managing older versions.

The base requirements are:

* Package the latest tripleo-heat-templates from the previous release
(in this case mitaka)
* Must be installable side-by-side with the the current version heat-templates
* A single srpm if at all possible

The patch essentially mimics what has been done downstream previously
and has generally worked.  Getting it to work with DLRN is more
difficult and sub-optimal due to having to track multiple upstream
branches.

I'm open to suggestions for how to deal with this challenge and am
certainly not stuck on the this being the solution.

Thanks

Mike

[1] http://review.rdoproject.org/r/2042