highlight buildpack version pining in README
trying to fix bundle behavior
overwrite config
remove bundle hack
use build dir for bundle
a better workaround
fix typo
trying to be smarter
fix typo
rewrite for now
Use absolute paths for setting BUNDLE_BUILD__RGEO
update build pack tag in README
Added ability to override s3 bucket where files are downloaded from with
environment variable
change libraries installation directory

Changed install directory from vendor/<library>/<version>/ to instead
install it all in .heroku/vendor so that this plays nice with other
buildpacks, such as heroku-buildpack-python.