Re-add jruby 9.1.17.0
Re-add jruby 9.1.17.0

9.1.17.0 requires ruby 2.3.x, while 9.2.0.0 requires ruby 2.5.x,
so we'll keep both version of jruby for now
[#157851009]

Signed-off-by: Andrew Meyer <8f92422f5861fc9f31873f75dd770facd670512b@pivotal.io>

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