.travis.yml in fluent-plugin-elapsed-time-0.0.7 vs .travis.yml in fluent-plugin-elapsed-time-0.0.8

@@ -1,6 +1,8 @@
 rvm:
-  - 1.9.3
-  - 2.0.0
   - 2.1.*
+  - 2.2.*
+  - 2.3.0
 gemfile:
   - Gemfile
+before_install:
+  - gem update bundler