Add openjdk-1.8.0_181, remove openjdk-1.8.0_172
Add openjdk-1.8.0_181, remove openjdk-1.8.0_172

[#159293112]

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

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