Update travis ruby versions and allowed failures

Seeing problems with jruby-head. I've moved it to allowed failures for
now to focus on immediate issues.

.travis.yml

@@ -3,12 +3,17 @@ bundler_args: --without doc
 rvm:
   - 1.8.7
   - 1.9.3
-  - 2.0.0
-  - 2.1.0
+  - 2.0
+  - 2.1
+  - rbx
+  - rbx-2
+  - jruby
   - ruby-head
-  - jruby-19mode
   - jruby-head
-  - rbx
+matrix:
+  allow_failures:
+    - rvm: ruby-head
+    - rvm: jruby-head
 notifications:
   email:
     - github@elskwid.net