This is a Heroku buildpack for vendoring binaries into your project. It doesn't do anything else, so to actually compile your app you should use heroku-buildpack-multi to combine it with a real buildpack.
$ ls
.vendor_urls
.buildpacks
$ heroku create --stack cedar --buildpack http://github.com/dollar/heroku-buildpack-multi.git
$ git push heroku master
...
-----> Heroku receiving push
-----> Fetching custom buildpack
-----> Found a .vendor_urls file
Vendoring https://s3.amazonaws.com/my-bucket/foo.tar.gz
...
The buildpack will detect that your app has a .vendor_urls
file in the root. Each line in this file will be treated as a URL pointing at a tarball to fetch and extract into your application's root directory.