.travis.yml in caze-0.2.1 vs .travis.yml in caze-0.2.2

@@ -1,5 +1,11 @@
 language: ruby
+sudo: false
+cache: bundler
 rvm:
-  - 2.0.0
-  - 2.1.0
-  - 2.2.2
+  - 2.3.6
+  - 2.4.3
+  - ruby-head
+
+matrix:
+  allow_failures:
+    - rvm: ruby-head