Fix Travis PHP 7 and HHVM builds.

.travis.yml

@@ -1,15 +1,17 @@
 language: php
 
-php:
-  - 5.2
-  - 5.3
-  - 5.4
-  - 5.5
-  - 5.6
-  - 7.0
-  - hhvm
-
-script:
-  - phpunit
-
 sudo: false
+
+matrix:
+  include:
+    - php: 5.2
+    - php: 5.3
+    - php: 5.4
+    - php: 5.5
+    - php: 5.6
+    - php: 7.0
+    - php: 7.1
+    - php: hhvm
+      dist: trusty
+
+script: vendor/bin/phpunit --verbose