Don't test on JRuby

Author: sferik

.travis.yml

@@ -1,23 +1,15 @@
 bundler_args: --without development
 language: ruby
-env:
-  global:
-    - JRUBY_OPTS="$JRUBY_OPTS --debug"
 rvm:
   - 1.8.7
   - 1.9.3
   - 2.0.0
   - 2.1.10
   - 2.2.6
   - 2.3.3
-  - jruby-18mode
-  - jruby-19mode
-  - jruby-9.1.6.0
   - ruby-head
 matrix:
   allow_failures:
-    - rvm: jruby-18mode
-    - rvm: jruby-19mode
     - rvm: ruby-head
   fast_finish: true
 script: bundle exec thor spec