Use the same version of bundler for both fs2,3
Use the same version of bundler for both fs2,3

Signed-off-by: Ben Fickes <b4731abca9c91b532f696cfd8fd7b4282be972df@pivotal.io>

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