2.15.1 is the first release that supports Rails 4.
2.15.1 is the first release that supports Rails 4.

specifically manifest.json

repinel/rails,gfvcastro/rails,richseviora/rails,Vasfed/rails,kamipo/rails,felipecvo/rails,rossta/rails,Erol/rails,deraru/rails,voray/rails,Envek/rails,marklocklear/rails,esparta/rails,gauravtiwari/rails,untidy-hair/rails,illacceptanything/illacceptanything,mtsmfm/rails,lcreid/rails,gcourtemanche/rails,yahonda/rails,bolek/rails,ledestin/rails,shioyama/rails,mathieujobin/reduced-rails-for-travis,vassilevsky/rails,xlymian/rails,kaspth/rails,xlymian/rails,arunagw/rails,untidy-hair/rails,marklocklear/rails,kachick/rails,sealocal/rails,rossta/rails,mechanicles/rails,repinel/rails,alecspopa/rails,printercu/rails,georgeclaghorn/rails,tgxworld/rails,arjes/rails,Erol/rails,MSP-Greg/rails,kaspth/rails,bogdanvlviv/rails,rails/rails,baerjam/rails,MichaelSp/rails,pschambacher/rails,alecspopa/rails,felipecvo/rails,arjes/rails,travisofthenorth/rails,EmmaB/rails-1,rbhitchcock/rails,voray/rails,illacceptanything/illacceptanything,mechanicles/rails,amoody2108/TechForJustice,baerjam/rails,lucasmazza/rails,yasslab/railsguides.jp,schuetzm/rails,printercu/rails,prathamesh-sonpatki/rails,yawboakye/rails,joonyou/rails,mijoharas/rails,notapatch/rails,illacceptanything/illacceptanything,Vasfed/rails,elfassy/rails,felipecvo/rails,schuetzm/rails,koic/rails,arunagw/rails,utilum/rails,pvalena/rails,travisofthenorth/rails,kmayer/rails,MSP-Greg/rails,Vasfed/rails,bradleypriest/rails,Spin42/rails,ttanimichi/rails,rails/rails,hanystudy/rails,aditya-kapoor/rails,odedniv/rails,ngpestelos/rails,rbhitchcock/rails,kmcphillips/rails,Stellenticket/rails,yahonda/rails,ledestin/rails,esparta/rails,tijwelch/rails,illacceptanything/illacceptanything,tjschuck/rails,bogdanvlviv/rails,Envek/rails,lcreid/rails,Vasfed/rails,marklocklear/rails,illacceptanything/illacceptanything,mijoharas/rails,illacceptanything/illacceptanything,jeremy/rails,sergey-alekseev/rails,kenta-s/rails,pvalena/rails,utilum/rails,riseshia/railsguides.kr,lcreid/rails,yalab/rails,betesh/rails,ttanimichi/rails,coreyward/rails,mechanicles/rails,fabianoleittes/rails,rafaelfranca/omg-rails,richseviora/rails,tgxworld/rails,printercu/rails,kirs/rails-1,Spin42/rails,mtsmfm/rails,kmcphillips/rails,coreyward/rails,mtsmfm/railstest,matrinox/rails,Erol/rails,lcreid/rails,iainbeeston/rails,yalab/rails,illacceptanything/illacceptanything,shioyama/rails,mohitnatoo/rails,kenta-s/rails,notapatch/rails,yawboakye/rails,gauravtiwari/rails,mohitnatoo/rails,mathieujobin/reduced-rails-for-travis,gfvcastro/rails,prathamesh-sonpatki/rails,utilum/rails,tjschuck/rails,mtsmfm/rails,flanger001/rails,kmayer/rails,tgxworld/rails,illacceptanything/illacceptanything,illacceptanything/illacceptanything,georgeclaghorn/rails,gavingmiller/rails,mtsmfm/railstest,riseshia/railsguides.kr,mohitnatoo/rails,iainbeeston/rails,sealocal/rails,fabianoleittes/rails,notapatch/rails,kddeisz/rails,amoody2108/TechForJustice,bolek/rails,voray/rails,stefanmb/rails,esparta/rails,iainbeeston/rails,xlymian/rails,vipulnsward/rails,coreyward/rails,tijwelch/rails,Stellenticket/rails,baerjam/rails,88rabbit/newRails,yahonda/rails,kirs/rails-1,joonyou/rails,brchristian/rails,repinel/rails,untidy-hair/rails,yhirano55/rails,palkan/rails,starknx/rails,kddeisz/rails,illacceptanything/illacceptanything,gavingmiller/rails,notapatch/rails,gcourtemanche/rails,kmcphillips/rails,illacceptanything/illacceptanything,bradleypriest/rails,rbhitchcock/rails,samphilipd/rails,ttanimichi/rails,gfvcastro/rails,BlakeWilliams/rails,vipulnsward/rails,tjschuck/rails,brchristian/rails,Spin42/rails,maicher/rails,EmmaB/rails-1,MichaelSp/rails,mechanicles/rails,eileencodes/rails,vipulnsward/rails,sealocal/rails,Sen-Zhang/rails,stefanmb/rails,kddeisz/rails,aditya-kapoor/rails,yalab/rails,yasslab/railsguides.jp,MSP-Greg/rails,MSP-Greg/rails,sergey-alekseev/rails,pvalena/rails,baerjam/rails,repinel/rails,yhirano55/rails,kachick/rails,88rabbit/newRails,joonyou/rails,eileencodes/rails,kamipo/rails,eileencodes/rails,Stellenticket/rails,stefanmb/rails,gcourtemanche/rails,prathamesh-sonpatki/rails,vassilevsky/rails,yasslab/railsguides.jp,kenta-s/rails,amoody2108/TechForJustice,betesh/rails,hanystudy/rails,betesh/rails,palkan/rails,illacceptanything/illacceptanything,Edouard-chin/rails,rafaelfranca/omg-rails,kmayer/rails,travisofthenorth/rails,rossta/rails,odedniv/rails,kirs/rails-1,vassilevsky/rails,deraru/rails,tijwelch/rails,aditya-kapoor/rails,EmmaB/rails-1,samphilipd/rails,ngpestelos/rails,yhirano55/rails,bogdanvlviv/rails,assain/rails,lucasmazza/rails,arunagw/rails,fabianoleittes/rails,lucasmazza/rails,yawboakye/rails,jeremy/rails,utilum/rails,elfassy/rails,Edouard-chin/rails,yawboakye/rails,joonyou/rails,MichaelSp/rails,bogdanvlviv/rails,samphilipd/rails,riseshia/railsguides.kr,georgeclaghorn/rails,Envek/rails,Edouard-chin/rails,gauravtiwari/rails,pschambacher/rails,yahonda/rails,flanger001/rails,tgxworld/rails,mijoharas/rails,untidy-hair/rails,assain/rails,ngpestelos/rails,pvalena/rails,BlakeWilliams/rails,palkan/rails,rails/rails,brchristian/rails,rafaelfranca/omg-rails,iainbeeston/rails,flanger001/rails,gavingmiller/rails,shioyama/rails,Envek/rails,Sen-Zhang/rails,kamipo/rails,Edouard-chin/rails,bolek/rails,richseviora/rails,esparta/rails,elfassy/rails,arjes/rails,yalab/rails,assain/rails,schuetzm/rails,starknx/rails,illacceptanything/illacceptanything,ledestin/rails,jeremy/rails,flanger001/rails,riseshia/railsguides.kr,betesh/rails,pschambacher/rails,starknx/rails,fabianoleittes/rails,hanystudy/rails,kaspth/rails,kddeisz/rails,88rabbit/newRails,arunagw/rails,maicher/rails,deraru/rails,eileencodes/rails,assain/rails,georgeclaghorn/rails,mathieujobin/reduced-rails-for-travis,illacceptanything/illacceptanything,matrinox/rails,prathamesh-sonpatki/rails,palkan/rails,shioyama/rails,alecspopa/rails,yasslab/railsguides.jp,matrinox/rails,Erol/rails,tjschuck/rails,schuetzm/rails,jeremy/rails,maicher/rails,odedniv/rails,printercu/rails,illacceptanything/illacceptanything,BlakeWilliams/rails,BlakeWilliams/rails,kmcphillips/rails,yhirano55/rails,gfvcastro/rails,bradleypriest/rails,vipulnsward/rails,Sen-Zhang/rails,mohitnatoo/rails,deraru/rails,koic/rails,rails/rails,aditya-kapoor/rails,kachick/rails,travisofthenorth/rails,mtsmfm/railstest,koic/rails,sergey-alekseev/rails,Stellenticket/rails