Buildpack can use dependencies provided by supply scripts
Buildpack can use dependencies provided by supply scripts

- only happens if bin/compile receives a deps dir argument and that dir
  exists

[#141616657]

Signed-off-by: Sam Smith <03a07629efb0a02c7bbe7cc340a4243da1ab861a@gmail.com>

ekaranto/rails4-bluemix-buildpack,cloudfoundry/ruby-buildpack,ekaranto/rails4-bluemix-buildpack,cloudfoundry/ruby-buildpack,cloudfoundry/ruby-buildpack,cloudfoundry/ruby-buildpack,ekaranto/rails4-bluemix-buildpack,cloudfoundry/ruby-buildpack,ekaranto/rails4-bluemix-buildpack