title: GitHub API: create a repository from template authenticated as installation
body: <p>I'm attempting to create a repository from a repository template via GitHub's API for an organization. <code>https://api.github.com/repos/{template_org_name}/{template_repo}/generate</code>. I'm trying to do so with a GitHub app authenticated as an installation with administrative permissions on the organization. I'm unable to successfully create a repository and get a <code>Resource not accessible by integration</code> response. I am, however, able to create a repository via this same endpoint using my own GitHub user's personal access token. I'm inclined to think that this endpoint is only available as a user-to-server request, but have not had any luck looking at docs (<a href="https://developer.github.com/v3/repos/#create-repository-using-a-repository-template" rel="nofollow noreferrer">https://developer.github.com/v3/repos/#create-repository-using-a-repository-template</a>). I understand that it is technically a beta endpoint, so maybe that is my answer.</p>
  
  <p>I checked that I am using the right "Accept" header as well in the request (<code>Accept: application/vnd.github.baptiste-preview+json</code>). Anyone have any luck with this endpoint? </p>