Move RubyGems 2.4.7 compatibility into 2.1+
Move RubyGems 2.4.7 compatibility into 2.1+

EasonYi/bundler,frsyuki/bundler,PG-kura/bundler,davydovanton/bundler,nju520/bundler,suhastech/bundler,ipmobiletech/bundler,schaary/bundler,asymmetric/bundler,masarakki/bundler,joshsoftware/bundler,gregkare/bundler,bundler/bundler,patvice/bundler,PG-kura/bundler,mvz/bundler,jingweno/bundler,ipmobiletech/bundler,bronzdoc/bundler,Eric-Guo/bundler,dilumnavanjana/bundler,cdwort/bundler,davydovanton/bundler,dilumnavanjana/bundler,RochesterinNYC/bundler,asutoshpalai/bundler,elovelan/bundler,pivotal-cf-experimental/bundler,kohgpat/bundler,byroot/bundler,jasonkarns/bundler,simplybusiness/bundler,mattbrictson/bundler-1,neslom/bundler,bundler/bundler,chulkilee/bundler,mpapis/bundler,carpodaster/bundler,chef/bundler,Teino1978-Corp/Teino1978-Corp-bundler,cstrahan/bundler,schaary/bundler,robinboening/bundler,robinboening/bundler,mpapis/bundler,agis-/bundler,masarakki/bundler,AiyionPrime/bundler,joshsoftware/bundler,lmtim/bundler,asutoshpalai/bundler,jingweno/bundler,mvz/bundler,RochesterinNYC/bundler,Wirachmat/bundler,lmtim/bundler,carpodaster/bundler,ximus/bundler,agis-/bundler,tgxworld/bundler,mdorrance/bundler,wenderjean/bundler,mdorrance/bundler,zhangkuaiji/bundler,elovelan/bundler,danimashu/bundler,patvice/bundler,christer155/bundler,neslom/bundler,asymmetric/bundler,danimashu/bundler,gregkare/bundler,nju520/bundler,Wirachmat/bundler,wenderjean/bundler,ximus/bundler,CorainChicago/bundler,EthanK28/bundler,Elffers/bundler,ligi/bundler,bronzdoc/bundler,EasonYi/bundler,seanlinsley/bundler,steved/bundler,philnash/bundler,anil826/bundler,christer155/bundler,philnash/bundler,CorainChicago/bundler,seanlinsley/bundler,cstrahan/bundler,frsyuki/bundler,zhangkuaiji/bundler,cdwort/bundler,h4ck3rm1k3/bundler,ngpestelos/bundler,kohgpat/bundler,h4ck3rm1k3/bundler,chulkilee/bundler,EthanK28/bundler,Elffers/bundler,jasonkarns/bundler,steved/bundler,suhastech/bundler,simplybusiness/bundler,roseweixel/bundler,byroot/bundler,Eric-Guo/bundler,anil826/bundler,Teino1978-Corp/Teino1978-Corp-bundler,AiyionPrime/bundler,pivotal-cf-experimental/bundler,ligi/bundler,chef/bundler,roseweixel/bundler,tgxworld/bundler,mattbrictson/bundler-1,ngpestelos/bundler