Update travis configuration.

Author: cmfcmf

.travis.yml

@@ -1,12 +1,22 @@
 language: php
-
-before_script:
-  - composer self-update
-  - composer install --dev --prefer-source
+sudo: false
 
 php:
   - 5.3
   - 5.4
   - 5.5
+  - 5.6
+  - hhvm
+  - nightly
+
+matrix:
+  fast_finish: true
+  allow_failures:
+    - php: hhvm
+    - php: nightly
+
+install:
+  - composer install --dev
+
 
 script: phpunit