Many apps deployed to Heroku require that multiple buildpacks be
configured in a particular order to operate correctly.
This updates the builtin Heroku provider's app resource to support
configuring buildpacks and the related documentation in the website.
Similar to config vars, externally set buildpacks will not be altered if
the config is not set.
The Terraform configuration syntax defines what arrays are.
Use the word array consistently throughout the documentation
instead of list.
The corresponding JSON datatype is called array as well, and
since the Terraform configuration syntax is interoperable with
JSON it makes sense to use the term array to describe them.
cc/ @catsby if you're curious. That fixed the acceptance tests,
thought there is still one (different issue) that is still failing.
Also, it nows construct a transport instead of using the default
and setting the auth globally. TF could potentially run things
concurrently and that might go wrong.
Bernerd Schaefer