Added PHP 5.6, 5.5 and HHVM to travis.yml

.travis.yml

@@ -1,7 +1,14 @@
 language: php
 php:
-  - 5.4
   - 5.3
+  - 5.4
+  - 5.5
+  - 5.6
+  - hhvm
+matrix:
+  allow_failures:
+    - php: hhvm
+  fast_finish: true
 before_script:
   - composer install --dev
   - composer update satooshi/php-coveralls --dev
@@ -12,4 +19,4 @@ after_script:
 notifications:
   recipients:
     - DL-PP-Platform-PHP-SDK@ebay.com
-  on_success: change
+  on_success: change