Indicate that specifying a gem to 'bundle show' is optional.
Indicate that specifying a gem to 'bundle show' is optional.

Closes #329
christer155/bundler,neslom/bundler,mvz/bundler,mattbrictson/bundler-1,mdorrance/bundler,elovelan/bundler,mattbrictson/bundler-1,davydovanton/bundler,twcctz500000/bundler,gregkare/bundler,lmtim/bundler,EthanK28/bundler,suhastech/bundler,schaary/bundler,Elffers/bundler,davydovanton/bundler,pjump/bundler,sideci-sample/sideci-sample-bundler,Eric-Guo/bundler,ngpestelos/bundler,carpodaster/bundler,agis-/bundler,Eric-Guo/bundler,kohgpat/bundler,bundler/bundler,Flameeyes/bundler,CorainChicago/bundler,CorainChicago/bundler,frsyuki/bundler,wenderjean/bundler,ipmobiletech/bundler,cstrahan/bundler,tgxworld/bundler,vemmaverve/bundler,pivotal-cf-experimental/bundler,joshsoftware/bundler,chef/bundler,r7kamura/bundler,jaym/bundler,MasterLambaster/bundler,asutoshpalai/bundler,elovelan/bundler,jasonkarns/bundler,seanlinsley/bundler,agis-/bundler,asutoshpalai/bundler,bronzdoc/bundler,ligi/bundler,jaym/bundler,steved/bundler,Elffers/bundler,neslom/bundler,rkh/bundler,frsyuki/bundler,smlance/bundler,EasonYi/bundler,philnash/bundler,danimashu/bundler,tgxworld/bundler,asymmetric/bundler,1337807/bundler,mdorrance/bundler,Teino1978-Corp/Teino1978-Corp-bundler,h4ck3rm1k3/bundler,JuanitoFatas/bundler,suhastech/bundler,EthanK28/bundler,mpapis/bundler,patvice/bundler,Wirachmat/bundler,dilumnavanjana/bundler,nju520/bundler,asymmetric/bundler,AiyionPrime/bundler,lgierth/bundler,ximus/bundler,raphael/bundler,RochesterinNYC/bundler,bundler/bundler,PG-kura/bundler,wenderjean/bundler,joshsoftware/bundler,chulkilee/bundler,trampoline/bundler,christer155/bundler,masarakki/bundler,seanlinsley/bundler,haonature888/bundler,masarakki/bundler,ligi/bundler,chef/bundler,cowboyd/bundler,roseweixel/bundler,carpodaster/bundler,simplybusiness/bundler,anil826/bundler,AiyionPrime/bundler,robinboening/bundler,chulkilee/bundler,jingweno/bundler,EasonYi/bundler,philnash/bundler,Wirachmat/bundler,steved/bundler,haonature/bundler,smlance/bundler,byroot/bundler,jasonkarns/bundler,dilumnavanjana/bundler,danimashu/bundler,RochesterinNYC/bundler,eagletmt/bundler,ducthanh/bundler,sideci-sample/sideci-sample-bundler,jingweno/bundler,gregkare/bundler,cdwort/bundler,anil826/bundler,haonaturel/bundler,pjump/bundler,schaary/bundler,nju520/bundler,kohgpat/bundler,patvice/bundler,ximus/bundler,bronzdoc/bundler,ngpestelos/bundler,h4ck3rm1k3/bundler,byroot/bundler,TimMoore/bundler,robinboening/bundler,lmtim/bundler,ipmobiletech/bundler,roseweixel/bundler,mvz/bundler,e2/bundler,cstrahan/bundler,TimMoore/bundler,haocafes/bundler,mpapis/bundler,simplybusiness/bundler,gentoo/bundler,zhangkuaiji/bundler,PG-kura/bundler,pivotal-cf-experimental/bundler,mtscout6/bundler,cdwort/bundler,Teino1978-Corp/Teino1978-Corp-bundler,zhangkuaiji/bundler