Add PHP 7.2 test in Travis CI

.travis.yml

@@ -33,6 +33,7 @@ matrix:
     after_success:
     - bash <(curl -s https://codecov.io/bash) -cF php
   - php: 7.1
+  - php: 7.2
   - node_js: 8
     language: node_js
     install: yarn

composer.json

@@ -42,6 +42,11 @@
       "tests"
     ]
   },
+  "scripts": {
+    "post-install-cmd": [
+      "unzip -o storage/patches/bs_php72_patch_180224.zip"
+    ]
+  },
   "config": {
     "preferred-install": "dist"
   }