Introduce linting npm script

Author: jedrzejchalubek

package.json

@@ -12,7 +12,8 @@
     "images:production": "cross-env NODE_ENV=production gulp image --gulpfile=build/build.js",
     "sass:lint": "cross-env NODE_ENV=production gulp sass:lint --gulpfile=build/build.js",
     "javascript:lint": "cross-env NODE_ENV=production gulp javascript:lint --gulpfile=build/build.js",
-    "precommit": "npm run sass:lint && npm run javascript:lint"
+    "lint": "npm run sass:lint && npm run javascript:lint",
+    "precommit": "npm run lint"
   },
   "dependencies": {},
   "devDependencies": {