Merge pull request #12 from abraham/pkg-ok

Add pkg-ok

Author: abraham

package.json

@@ -10,6 +10,7 @@
     "clean": "rimraf dist",
     "prebuild": "npm run clean",
     "prepare": "npm run build",
+    "prepublishOnly": "pkg-ok",
     "start": "jest --watch",
     "test": "jest"
   },
@@ -35,6 +36,7 @@
   "devDependencies": {
     "@types/jest": "23.3.0",
     "jest": "23.4.1",
+    "pkg-ok": "2.2.0",
     "rimraf": "2.6.2",
     "ts-jest": "23.0.1",
     "typescript": "2.9.2"