.travis.yml in imap-backup-1.0.17 vs .travis.yml in imap-backup-1.1.0

@@ -1,9 +1,14 @@
 language: ruby
 rvm:
   - 1.9.3
   - 2.0.0
-  - 2.1.1
+  - 2.1.5
+  - 2.2.4
+  - 2.3.0
 branches:
   only:
     - master
+before_install:
+  - gem update --system
+  - gem update bundler
 script: "bundle exec rake spec"