Add assets task

package.json

@@ -8,6 +8,7 @@
     "build:pages": "babel-node ./tasks/build.js",
     "build:js": "webpack --config webpack.config.js",
     "build:css": "postcss -c postcss.config.json -o dist/styles.css styles/main.css",
+    "build:assets": "babel-node ./tasks/assets.js",
     "watch": "babel-node ./tasks/watch.js",
     "clean": "babel-node ./tasks/clean.js",
     "test": "echo \"Error: no test specified\" && exit 1"