add travis config

.travis.yml

@@ -0,0 +1,13 @@
+script: bundle exec rake spec
+
+rvm:
+  - 1.8.7
+  - 1.9.2
+  - 1.9.3
+
+notifications:
+  webhooks:
+    on_success: always
+    on_failure: always
+    urls:
+      - https://dx-helper.herokuapp.com/travis