Implement NPM format:pretty script/task for Prettier

To allow to format all sources the `format:pretty` NPM script/task has
been added as well as the `format` script/task to run all tasks of the
formatting workflow.

Epic: GH-33
Depends on GH-47 GH-49
Resolves GH-37

package.json

@@ -26,8 +26,10 @@
     "arcticicestudio"
   ],
   "scripts": {
-    "lint": "npm-run-all lint:*",
-    "lint:md": "remark --no-stdout . \".github/**/*.md\""
+    "format:pretty": "prettier --write \"./**/*.{js,json,md,yml}\"",
+    "format": "npm-run-all format:pretty",
+    "lint:md": "remark --no-stdout . \".github/**/*.md\"",
+    "lint": "npm-run-all lint:*"
   },
   "devDependencies": {
     "npm-run-all": "4.1.5",