reword readme
reword readme

  - remove upgrading from 0.8 and 0.9
  - reword intro paragraph
  - move build badge to the right of the title
joshsoftware/bundler,twcctz500000/bundler,TimMoore/bundler,mpapis/bundler,steved/bundler,mdorrance/bundler,seanlinsley/bundler,carpodaster/bundler,cstrahan/bundler,PG-kura/bundler,lmtim/bundler,jingweno/bundler,frsyuki/bundler,robinboening/bundler,PG-kura/bundler,roseweixel/bundler,christer155/bundler,lmtim/bundler,ipmobiletech/bundler,neslom/bundler,1337807/bundler,byroot/bundler,mvz/bundler,schaary/bundler,haonature888/bundler,danimashu/bundler,agis-/bundler,steved/bundler,wenderjean/bundler,asymmetric/bundler,byroot/bundler,mpapis/bundler,EthanK28/bundler,kohgpat/bundler,ligi/bundler,jasonkarns/bundler,mattbrictson/bundler-1,ngpestelos/bundler,masarakki/bundler,RochesterinNYC/bundler,simplybusiness/bundler,asutoshpalai/bundler,elovelan/bundler,haonaturel/bundler,zhangkuaiji/bundler,cdwort/bundler,davydovanton/bundler,anil826/bundler,patvice/bundler,JuanitoFatas/bundler,smlance/bundler,ligi/bundler,CorainChicago/bundler,jaym/bundler,kohgpat/bundler,ipmobiletech/bundler,mdorrance/bundler,chulkilee/bundler,ximus/bundler,simplybusiness/bundler,Eric-Guo/bundler,cstrahan/bundler,davydovanton/bundler,pjump/bundler,dilumnavanjana/bundler,bundler/bundler,pivotal-cf-experimental/bundler,Elffers/bundler,EasonYi/bundler,jaym/bundler,zhangkuaiji/bundler,suhastech/bundler,roseweixel/bundler,Wirachmat/bundler,masarakki/bundler,jingweno/bundler,EthanK28/bundler,CorainChicago/bundler,nju520/bundler,philnash/bundler,philnash/bundler,bronzdoc/bundler,Teino1978-Corp/Teino1978-Corp-bundler,ngpestelos/bundler,sideci-sample/sideci-sample-bundler,wenderjean/bundler,chef/bundler,bronzdoc/bundler,ximus/bundler,patvice/bundler,suhastech/bundler,rkh/bundler,joshsoftware/bundler,RochesterinNYC/bundler,Wirachmat/bundler,robinboening/bundler,carpodaster/bundler,Teino1978-Corp/Teino1978-Corp-bundler,eagletmt/bundler,asutoshpalai/bundler,e2/bundler,smlance/bundler,cdwort/bundler,seanlinsley/bundler,chef/bundler,nju520/bundler,AiyionPrime/bundler,tgxworld/bundler,jasonkarns/bundler,christer155/bundler,Elffers/bundler,asymmetric/bundler,bundler/bundler,gregkare/bundler,agis-/bundler,tgxworld/bundler,mvz/bundler,EasonYi/bundler,h4ck3rm1k3/bundler,AiyionPrime/bundler,frsyuki/bundler,gregkare/bundler,anil826/bundler,h4ck3rm1k3/bundler,r7kamura/bundler,neslom/bundler,pivotal-cf-experimental/bundler,Eric-Guo/bundler,chulkilee/bundler,elovelan/bundler,TimMoore/bundler,dilumnavanjana/bundler,danimashu/bundler,mattbrictson/bundler-1,haonature/bundler,vemmaverve/bundler,schaary/bundler,sideci-sample/sideci-sample-bundler,haocafes/bundler,pjump/bundler