Update the bundler version to 1.6.3
Update the bundler version to 1.6.3

[#72215322]

ibmdb/db2rubybuildpack,Altoros/ruby-buildpack,fcruxen/ruby-buildpack,fcruxen/ruby-buildpack,takii/db2rubybuildpack,jumptvs/BP_Ruby,cloudn/buildpack-ruby,CPPWind/ruby-buildpack,Scalingo/ruby-buildpack,ekaranto/rails4-bluemix-buildpack,hatofmonkeys/ruby-testing-buildpack,hpcloud/ruby-buildpack,CPPWind/ruby-buildpack,ablease/custom-buildpack,cloudfoundry/ruby-buildpack,cloudn/buildpack-ruby,hatofmonkeys/ruby-testing-buildpack,cloudn/buildpack-ruby,iamjarvo/ruby-buildpack,Jonty/ruby-buildpack,cloudfoundry/ruby-buildpack,cloudfoundry/ruby-buildpack,sky-uk/ruby-buildpack,jumptvs/BP_Ruby,ablease/custom-buildpack,ekaranto/rails4-bluemix-buildpack,fcruxen/ruby-buildpack,ekaranto/rails4-bluemix-buildpack,cloudn/buildpack-ruby,hpcloud/ruby-buildpack,bskyb-commerce/ruby-buildpack,bskyb-commerce/ruby-buildpack,Jonty/ruby-buildpack,iamjarvo/ruby-buildpack,bskyb-commerce/ruby-buildpack,ablease/custom-buildpack,takii/db2rubybuildpack,ibmdb/db2rubybuildpack,sky-uk/ruby-buildpack,Altoros/ruby-buildpack,CPPWind/ruby-buildpack,Altoros/ruby-buildpack,cloudfoundry/ruby-buildpack,Jonty/ruby-buildpack,iamjarvo/ruby-buildpack,ekaranto/rails4-bluemix-buildpack,CPPWind/ruby-buildpack,Altoros/ruby-buildpack,sky-uk/ruby-buildpack,iamjarvo/ruby-buildpack,hpcloud/ruby-buildpack,Scalingo/ruby-buildpack,fcruxen/ruby-buildpack,ablease/custom-buildpack,ibmdb/db2rubybuildpack,hpcloud/ruby-buildpack,bskyb-commerce/ruby-buildpack,hatofmonkeys/ruby-testing-buildpack,jumptvs/BP_Ruby,takii/db2rubybuildpack,cloudfoundry/ruby-buildpack,sky-uk/ruby-buildpack,jumptvs/BP_Ruby,takii/db2rubybuildpack,Jonty/ruby-buildpack