.travis.yml in heartcheck-1.1.0 vs .travis.yml in heartcheck-1.1.1

@@ -1,12 +1,18 @@
 language: ruby
-rvm:
-  - "1.9.3"
-  - "2.0.0"
-  - "2.1.0"
-  - "2.1.5"
-  - "2.2.1"
-  - "2.2.2"
-  - "2.3.0"
 install: bundle install -j 4 --retry 3
 script:
   - bin/rspec
+matrix:
+  include:
+    - rvm: "1.9.3"
+      gemfile: Gemfile-old-ruby
+    - rvm: "2.0.0"
+      gemfile: Gemfile-old-ruby
+    - rvm: "2.1.0"
+      gemfile: Gemfile-old-ruby
+    - rvm: "2.1.5"
+      gemfile: Gemfile-old-ruby
+    - rvm: "2.2.1"
+      gemfile: Gemfile-old-ruby
+    - rvm: "2.2.2"
+    - rvm: "2.3.0"