.travis.yml in libsvmloader-0.1.3 vs .travis.yml in libsvmloader-0.2.0

@@ -1,5 +1,10 @@
 sudo: false
+os: linux
+dist: trusty
 language: ruby
 rvm:
-  - 2.4.1
+  - 2.2
+  - 2.3
+  - 2.4
+  - 2.5
 before_install: gem install bundler -v 1.15.3