.travis.yml in sucker_punch-1.5.1 vs .travis.yml in sucker_punch-1.6.0

@@ -2,9 +2,10 @@
 rvm:
   - 1.9.3
   - jruby-19mode
   - rbx-2
   - 2.0.0
+  - 2.1.0
   - ruby-head
 matrix:
   allow_failures:
     - rvm: jruby-19mode
     - rvm: rbx-2