My first pull request, apologies if I've done anything incorrectly, also I just noticed you've been making some changes to the development branch so it could be the issues I was running into have been corrected by now.
By motivation for creating the R-3.1.0 branch was to get the ggplot2 package working correctly, specifically ggsave was failing for me. I probably made too many extraneous changes in the process of getting this going, but figured I would create a pull request, and if there is anything that is useful for you to pull into the main branch, great, if not, no worries.
So a summary of the changes I made:
updated support section to use R 3.1 and removed old vulcan files
updated / added some tests
update binaries used by the buildpack
fix binaries url
some minor changes to compile file
update R binary URL