Add method to retrieve stack template, Avoid redirects

[mchill]

Allows the user to retrieve the heat template that a stack was created with. The path was ending with a /, which breaks the API call, so I set the URL in templates.js.

If you go to the path ../stacks/<stack_id>, you are (supposed to be) redirected to the proper path, ../stacks/<stack_name>/<stack_id>. Whether it's a bug with our deployment or OpenStack in general, the redirect for stack updates doesn't work. This change allows the user to go directly to the correct path by specifying the stack name.