.travis.yml in middleman-webp-0.2.6 vs .travis.yml in middleman-webp-0.2.7

@@ -1,9 +1,10 @@
 language: ruby
 rvm:
   - 1.9.3
   - 2.0.0
-  - 2.1.0
+  - 2.1.5
+  - 2.2.1
 script: bundle exec rake test
 before_install:
   - sudo apt-get update -qq
   - sudo apt-get install webp