Run tests on PHP 7.0 and 7.1 (#554)

With failures allowed for 7.0 and 7.1 and fast finish enabled.

Author: mheijkoop

.travis.yml

@@ -15,5 +15,13 @@ php:
   - 5.3
   - 5.4
   - 5.5
+  - 7.0
+  - 7.1
+
+matrix:
+  allow_failures:
+    - php: 7.0
+    - php: 7.1
+  fast_finish: true
 
 script: ./vendor/bin/phpunit