Adds a pdftk wrapper script so the pdftk-java apt package will run on heroku

The heroku-community/apt buildpack is mostly-successful at installing apt packages and .deb files, but it doesn't run post-install scripts and it installs everything in the /app/.apt directory.

This buildpack just creates a custom wrapper script that's aware that all the apt packages are installed in /app/.apt instead of the system root.

This buildpack is not meant to be used on its own, and instead should be in used in combination with Heroku's multiple buildpack support.

You will need the heroku/jvm buildpack, the heroku-community/apt buildpack, and an Aptfile that installs pdftk and its relevant dependencies

Example Aptfile:

libbcprov-java
libcommons-lang3-java
http://mirrors.kernel.org/ubuntu/pool/universe/p/pdftk-java/pdftk-java_3.0.6-1_all.deb

MIT