Add PHP 5.6 (currently alpha) to .travis.yml
diff --git a/.travis.yml b/.travis.yml
index 718e6aa..1d35629 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,6 +4,7 @@
   - 5.3
   - 5.4
   - 5.5
+  - 5.6
   - hhvm
   
 env: