.travis.yml in fluent-plugin-numeric-counter-0.2.2 vs .travis.yml in fluent-plugin-numeric-counter-0.2.3

@@ -1,4 +1,6 @@
 language: ruby
 rvm:
   - 1.9.3
   - 2.0.0
+  - 2.1
+  - 2.2