check for the proper binstubs for Rails 4
check for the proper binstubs for Rails 4

sky-uk/ruby-buildpack,scottatron/moc-buildpack,schu/buildpack-testing,ekaranto/rails4-bluemix-buildpack,sky-uk/help-heroku-buildpack,ChefSteps/heroku-buildpack-ruby,packetmonkey/heroku-buildpack-ruby,Scalingo/ruby-buildpack,d-reinhold/cf-buildpack-ruby,tomwolfe/heroku-buildpack-gsl-ruby,pkgr/buildpack-ruby-precise-old,packetmonkey/heroku-buildpack-ruby,DyegoCosta/heroku-buildpack-ruby,sky-uk/help-heroku-buildpack,electricobjects/heroku-buildpack-ruby,andycroll/heroku-buildpack-jekyll,shuber/heroku-buildpack-ruby,makifund/heroku-buildpack-ruby,mperejda/heroku-buildpack-ruby,heroku/heroku-buildpack-ruby,jonseaberg/heroku-buildpack-turbo-sprockets,pilotcreative/heroku-buildpack-ruby,jayshreeanand/heroku-buildpack-ruby,sanemat/heroku-buildpack-ruby-tachikoma,awebneck/heroku-buildpack-canvas,instacart/heroku-buildpack-ruby,lyoshenka/heroku-buildpack-ruby-jekyll,qstream/heroku-buildpack-ruby,shuber/heroku-buildpack-ruby,aarongray/heroku-buildpack-ruby,jonasoberschweiber/heroku-buildpack-ruby,takii/db2rubybuildpack,ndbroadbent/heroku-buildpack-turbo-sprockets,zoomer/heroku-buildpack-ruby-bower,mperejda/heroku-buildpack-ruby,ltrademark/heroku-buildpack-ruby,dtao/teeny-buildpack,travis-ci/heroku-buildpack-ruby,jumptvs/BP_Ruby,jeremyvdw/heroku-buildpack-ruby-jekyll,Scalingo/ruby-buildpack,cloudControl/buildpack-ruby,mrhenry/heroku-buildpack-ruby,michaelphines/alexa-nest,ruby/heroku-buildpack-www-ruby-lang,ericboehs/heroku-buildpack-ruby,ekaranto/rails4-bluemix-buildpack,heroku/heroku-buildpack-ruby,sky-uk/ruby-buildpack,iamjarvo/ruby-buildpack,orenyk/heroku-buildpack-ruby,leonardykris/mos-ruby-buildpack,gls1/heroku-buildpack-ruby-pdftk,jumptvs/BP_Ruby,allomov/fat-free-heroku-buildpack-ruby,davidjrice/heroku-buildpack-couchbase-ruby,sstelfox/buildpack-ruby,instacart/heroku-buildpack-ruby,KoanHealth/heroku-buildpack-marvin-setup,cloudn/buildpack-ruby,simonnordberg/heroku-buildpack-ruby,KoanHealth/heroku-buildpack-marvin-setup,ActiveState/heroku-buildpack-ruby,crdschurch/heroku-buildpack-ruby,d-reinhold/cf-buildpack-ruby,diasks2/heroku-buildpack-mecab,righi/instacart-heroku-buildpack,travis-ci/heroku-buildpack-ruby,takii/heroku-buildpack-ruby,cloudfoundry/ruby-buildpack,stefansundin/heroku-buildpack-ruby,jgable/buildpack-ruby-rack-setup-tasks,Git-Host/prelang-buildpack,cloudn/buildpack-ruby,takii/db2rubybuildpack,wakermahmud/heroku-buildpack-jekyll,makifund/heroku-buildpack-ruby,wolfoo2931/heroku-buildpack-ruby-2a352ae,rowanoulton/heroku-buildpack-ruby,cmaggard/heroku-buildpack-turbo-sprockets,phusion/heroku-buildpack-ruby,AdStage/heroku-buildpack-ruby,bwaite-jaroop/heroku-buildpack-ruby,electricobjects/heroku-buildpack-ruby,catalyzeio/buildpack-ruby,DouglasAllen/heroku-buildpack-ruby,dieze/heroku-buildpack-ruby-hooks,cloudn/buildpack-ruby,beydogan/ruby-buildpack,davidjrice/heroku-buildpack-couchbase-ruby,dleavitt/heroku-buildpack-ruby,bskyb-commerce/ruby-buildpack,derrek/heroku-buildpack-ruby,sstelfox/buildpack-ruby,derrek/heroku-buildpack-ruby,redhotvengeance/heroku-buildpack-deep-thought,fcruxen/ruby-buildpack,Jonty/ruby-buildpack,zidekmat/buildpack-ruby,ChefSteps/heroku-buildpack-ruby,Nedomas/heroku-buildpack-ruby-minus-node-with-node-paths,pilotcreative/heroku-buildpack-ruby,Dim25/heroku-buildpack-ruby-GSL,stolt45/heroku-buildpack-ruby-with-sqlite3,hpcloud/heroku-buildpack-ruby,simonnordberg/heroku-buildpack-ruby,samfrench/heroku-buildpack-ruby,ActiveState/heroku-buildpack-ruby,donnykurnia/heroku-buildpack-ruby,orenyk/heroku-buildpack-ruby,Altoros/ruby-buildpack,rhomobile/heroku-buildpack-ruby,thewebguy/heroku-buildpack-ruby-ffmpeg-libsndfile,rvizza/heroku-buildpack-gsl-ruby,Jonty/ruby-buildpack,dlorson/gentle-buildpack,dtao/deft-buildpack-ruby,Dim25/heroku-buildpack-ruby-GSL,trumaker/heroku-buildpack-turbo-sprockets,dtao/teeny-buildpack,phusion/heroku-buildpack-ruby,brightbytes/heroku-buildpack-ruby-without-assets-precompile,bellycard/heroku-buildpack-ruby,mintybit/heroku-buildpack-ruby,0x00evil/heroku-buildpack-ruby,fgbreel/heroku-buildpack-ruby,bskyb-commerce/help-heroku-buildpack,space150/heroku-buildpack-ruby,ibmdb/db2rubybuildpack,qnyp/heroku-buildpack-ruby-bower,Micka33/heroku-buildpack-ruby-liblua,sky-uk/ruby-buildpack,davidjrice/heroku-buildpack-couchbase-ruby,pkgr/heroku-buildpack-ruby,ascot21/heroku-buildpack-turbo-sprockets,orlando/heroku-buildpack-ruby,d-reinhold/cf-buildpack-ruby,DyegoCosta/heroku-buildpack-ruby,ekaranto/rails4-bluemix-buildpack,vhx/heroku-buildpack,Altoros/ruby-buildpack,mattwalters/heroku-buildpack-ruby,schu/buildpack-testing,cloudfoundry/ruby-buildpack,erintherad/heroku-buildpack-ruby,andycroll/heroku-buildpack-jekyll,pkgr/heroku-buildpack-ruby,anay/buildpack-ruby-with-oracle-jdk,gbenedict/heroku-buildpack-ruby,swipesense/heroku-buildpack-ruby,redhotvengeance/heroku-buildpack-deep-thought,jasonlevens/heroku-buildpack-ruby,cloudfoundry/ruby-buildpack,blueapron/heroku-buildpack-ruby,swipesense/heroku-buildpack-ruby,jumptvs/BP_Ruby,cloudfoundry/ruby-buildpack,mintybit/heroku-buildpack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oku-buildpack-ruby-tpope,icelab/heroku-buildpack-ruby,tdenovan/heroku-buildpack-ruby,teodor-pripoae/heroku-buildpack-ruby,Nedomas/heroku-buildpack-ruby-minus-node-with-node-paths,gls1/heroku-buildpack-ruby-pdftk-new,Genius/heroku-buildpack-ruby,allomov/fat-free-heroku-buildpack-ruby,AdStage/heroku-buildpack-ruby,codykrieger/heroku-buildpack-jekyll,cloudfoundry/ruby-buildpack,vhx/heroku-buildpack,orlando/heroku-buildpack-ruby,Altoros/ruby-buildpack,crdschurch/heroku-buildpack-ruby