Added ruby-head and jruby-head as Travis build targets (with allow_failure).

Author: jdantonio

.travis.yml

@@ -4,5 +4,11 @@ rvm:
   - 2.0.0
   - 1.9.3
   - 1.9.2
-  - rbx-2
+  - ruby-head
   - jruby-19mode
+  - jruby-head
+  - rbx-2
+matrix:
+  allow_failures:
+    - rvm: ruby-head
+    - rvm: jruby-head