heroku-buildpack-ruby

Revert "Merge pull request #555 from heroku/schneems/re-organize-bin"

This reverts commit a23dca10fbd8d523cfc7d6847d0d648a4fc0fdec, reversing
changes made to 850d4c0b2decc76d6102799a8ffc04601958a223.

This is temporary, we need to seperate out code into two deploys. One
for default ruby version, then this in another deploy.