pass bin/release $build_root instead of $app_root

Needed by heroku-buildpack-ruby
Merge pull request #56 from icco/patch-1

pass bin/release $build_root instead of $app_root
Use https://github.com/CHH/heroku-buildpack-php as the builtin PHP buildpack
Merge pull request #57 from qrohlf/patch-1

Use https://github.com/CHH/heroku-buildpack-php as the builtin PHP buildpack
use the build root to build the release file
updating authors
adding revel buildpack