Drop JRuby 1.9

Since we are no longer support Ruby 1.9 we are safe to remove this from the CI.

Author: maurogeorge

.travis.yml

@@ -32,8 +32,6 @@ matrix:
   include:
   - rvm: 2.2
     env: CAPTURE_STDERR=true
-  - rvm: jruby-19mode
-    env: JRUBY_OPTS='--server -Xcompile.invokedynamic=false -Xcli.debug=true --debug'
   allow_failures:
     - rvm: ruby-head
   fast_finish: true