Add bundler 1.16.0, remove bundler 1.15.4
Add bundler 1.16.0, remove bundler 1.15.4

source url: https://rubygems.org/downloads/bundler-1.16.0.gem
source sha256: 084e7ebe90cc5236520ad49d4c5d9f58b19a98751a249070296a5943f88adb74

[#152452239]

cloudfoundry/ruby-buildpack,cloudfoundry/ruby-buildpack,cloudfoundry/ruby-buildpack,cloudfoundry/ruby-buildpack,cloudfoundry/ruby-buildpack