.travis.yml in hamlit-block-0.7.0 vs .travis.yml in hamlit-block-0.7.1

@@ -1,4 +1,6 @@
 language: ruby
 rvm:
-  - 2.2.3
-before_install: gem install bundler -v 1.11.2
+  - 2.3
+  - 2.4
+  - 2.5
+  - 2.6