Match Grape's build matrix.

Author: dblock

.travis.yml

@@ -1,7 +1,18 @@
 language: ruby
+
 cache: bundler
+
 rvm:
+  - ruby-head
+  - 2.1.1
+  - 2.1.0
   - 2.0.0
   - 1.9.3
   - jruby-19mode
+  - jruby-head
   - rbx-2
+
+matrix:
+  allow_failures:
+    - rvm: ruby-head
+    - rvm: jruby-head