Added husky (#251)

* Added husky

* Lint on precommit

package.json

@@ -9,7 +9,9 @@
     "lib"
   ],
   "scripts": {
-    "test": "xo && ava",
+    "precommit": "npm run lint",
+    "lint": "xo",
+    "test": "npm run lint && ava",
     "pack": "pkg . --out-dir packed"
   },
   "pkg": {
@@ -87,6 +89,7 @@
   "devDependencies": {
     "alpha-sort": "^2.0.0",
     "ava": "^0.17.0",
+    "husky": "^0.13.1",
     "pkg": "^3.0.0-beta.22",
     "xo": "^0.17.1"
   }