.travis.yml in le-2.7.3 vs .travis.yml in le-2.7.4

@@ -1,7 +1,8 @@
 language: ruby
 rvm:
+  - 2.3.1
   - 2.0.0
   - 1.9.3
   - jruby-19mode
 before_install:
-  - gem install bundler
\ No newline at end of file
+  - gem install bundler