Added husky (Git hooks) dependency and pre-push hook to package.json

Author: holgerd77

package.json

@@ -16,6 +16,11 @@
     "test:build": "npm run build:dist && mocha ./test/*.js",
     "build:dist": "babel src/ -d ."
   },
+  "husky": {
+    "hooks": {
+      "pre-push": "npm run lint"
+    }
+  },
   "repository": {
     "type": "git",
     "url": "https://github.com/ethereumjs/ethereumjs-wallet.git"
@@ -46,6 +51,7 @@
     "babel-cli": "^6.26.0",
     "babel-preset-env": "^1.7.0",
     "coveralls": "^3.0.0",
+    "husky": "^2.1.0",
     "istanbul": "^0.4.5",
     "mocha": "^5.2.0",
     "standard": "^12.0.0"