Run tests on CRuby 2.4

Hiroshi Nakamura · Hiroshi Nakamura · commit 1b9eeccaa5aa · 2017-04-16T22:30:31.000+09:00
diff --git a/.travis.yml b/.travis.yml
@@ -5,6 +5,7 @@ rvm:
   - 2.1.8
   - 2.2.4
   - 2.3.0
+  - 2.4.0
   - ruby-head
   - jruby-19mode
   - jruby-head
