add hallmark devDependency

Author: vweevers

package.json

@@ -3,7 +3,8 @@
   "version": "0.0.2",
   "description": "Reusable list of browsers to test against when using Airtap",
   "scripts": {
-    "test": "standard && node test.js"
+    "test": "standard && hallmark && node test.js",
+    "hallmark": "hallmark --fix"
   },
   "repository": "airtap/browsers",
   "keywords": [
@@ -19,6 +20,7 @@
   },
   "homepage": "https://github.com/airtap/browsers",
   "devDependencies": {
+    "hallmark": "^0.1.0",
     "standard": "^12.0.0",
     "tape": "^4.8.0"
   },