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

@@ -1,5 +1,10 @@
 sudo: false
+os: linux
+dist: trusty
 language: ruby
 rvm:
-  - 2.4.2
-before_install: gem install bundler -v 1.15.4
+  - 2.2.9
+  - 2.3.6
+  - 2.4.3
+before_install:
+  - gem install --no-document bundler -v '~> 1.16'