Test on jruby-9.1.16.0
Test on jruby-9.1.16.0

Some HTTP.rb tests didn't work on JRuby due to a bug in IO.copy_stream,
which jruby-9.1.16.0 fixed, so we tell Travis CI to use that version.

pezra/http.rb,httprb/http.rb,httprb/http