Test on PHP 7

Author: GrahamCampbell

.travis.yml

@@ -1,13 +1,27 @@
 language: php
 
-php:
-  - 5.4
-  - 5.5
-  - 5.6
-  - hhvm
+matrix:
+  include:
+    - php: 5.4
+      dist: trusty
+    - php: 5.5
+      dist: trusty
+    - php: 5.6
+      dist: trusty
+    - php: 7.0
+      dist: trusty
+    - php: 7.1
+      dist: bionic
+    - php: 7.2
+      dist: bionic
+    - php: 7.3
+      dist: bionic
+    - php: 7.4
+      dist: bionic
+    - php: hhvm-3.18
+      dist: trusty
 
-before_script:
-  - composer install
+install: travis_retry composer install
 
 script: make test