.travis.yml in fluent-plugin-twitter-0.5.3 vs .travis.yml in fluent-plugin-twitter-0.5.4

@@ -1,18 +1,28 @@
 sudo: false
 language: ruby
 
 rvm:
-  - 2.3.0
   - 2.2
   - 2.1
-  - 2.0.0
-  - 1.9.3
 
 before_install:
   - gem update bundler
 
 gemfile:
   - Gemfile
   - gemfiles/fluentd_v0.10.gemfile
   - gemfiles/fluentd_v0.12.gemfile
+
+matrix:
+  include:
+    - rvm: 2.3.1
+      gemfile: Gemfile
+    - rvm: 2.0.0
+      gemfile: gemfiles/fluentd_v0.10.gemfile
+    - rvm: 2.0.0
+      gemfile: gemfiles/fluentd_v0.12.gemfile
+    - rvm: 1.9.3
+      gemfile: gemfiles/fluentd_v0.10.gemfile
+    - rvm: 1.9.3
+      gemfile: gemfiles/fluentd_v0.12.gemfile