Added PHP 5.6 and HHVM to travis.yml

Author: Nyholm

.travis.yml

@@ -6,6 +6,12 @@ php:
   - 5.3
   - 5.4
   - 5.5
+  - 5.6
+  - hhvm
+ 
+matrix:
+    allow_failures:
+        - php: hhvm
 
 script:
  - phpunit -c ./unitTests/