chore(build): add cdn fields

Author: bigopon

package.json

@@ -14,6 +14,9 @@
   "license": "MIT",
   "author": "Jeremy Danyow <jdanyow@gmail.com> (https:/danyow.net/)",
   "main": "dist/commonjs/aurelia-validation.js",
+  "module": "dist/es2015/aurelia-validation.js",
+  "browser": "dist/umd/aurelia-validation.js",
+  "unpkg": "dist/umd/aurelia-validation.js",
   "types": "dist/aurelia-validation.d.ts",
   "typings": "dist/aurelia-validation.d.ts",
   "repository": {