travis: test php 5.3..7.3

.travis.yml

@@ -1,21 +1,26 @@
 language: php
 sudo: false
+dist: trusty
 
-php:
+jobs:
-  - 7.0
+  fast_finish: true
-  - 5.6
+  allow_failures:
-  - 5.5
+    - php: "hhvm"
-  - 5.4
+  include:
-  - hhvm
+    - php: "5.3"
+      dist: precise
+    - php: "5.4"
+    - php: "5.5"
+    - php: "5.6"
+    - php: "7.0"
+    - php: "7.1"
+    - php: "7.2"
+    - php: "nightly"
+    - php: "hhvm"
 
 env:
   - CLOSURE_VERSION: 20161024
 
-matrix:
-  allow_failures:
-    - php: hhvm
-    - php: 7.0
-
 services:
   - memcached