.travis.yml in gibbon-3.2.0 vs .travis.yml in gibbon-3.3.0

@@ -2,9 +2,10 @@
 sudo: false
 cache: bundler
 before_install:
   - gem install bundler # -v 1.7.14 if a specific version is needed
 rvm:
-  - 2.0.0
   - 2.1.5
   - 2.2.2
-  - 2.3.3
\ No newline at end of file
+  - 2.3.8
+  - 2.4.5
+  - 2.5.3