change template for existing (placeholder) release Merged

Once a Release has been created, there's no way to apply a template or change the Release to copy another Release. That makes us hesitant to create a Release until we know pretty well what's going to go into it, when other Aha! tools suggest that the Release would be a great way to bring visibility to the discovery process and to the early stages of our projects.

This would be particularly useful in conjunction with APP-I-1786. We'd expand the Release workflow back through more types of "Under Consideration" and track discovery of our projects much more thoroughly.

I'd like to be able to create a blank/placeholder Release very early in our project planning process, make the links to Goals and Initiatives to show stakeholders why we're working on this, build in Features that start to identify how we're going to deliver value in the project -- and only then decide what kind of Release template to work from, once I've investigated feasibility and value. Seems like the best way to do that would be to be able to apply a template to an existing Release, not just have those options when first creating the Release.