.travis.yml in mongoid-history-0.2.3 vs .travis.yml in mongoid-history-0.2.4

@@ -1,4 +1,10 @@
 language: ruby
 rvm:
   - 1.9.2
   - 1.9.3
+  - 1.9.3
+  - ruby-head
+  - jruby
+  - rbx
+  - ree
+