Add best practice to prefer Lo-dash/Underscore

There are certain utility methods that exist in both Lo-dash/Underscore as well
as in a framework like AngularJS. We should prefer the former, because they are
smaller, well-focused, widely used libraries. This will avoid us from coupling
our code to a framework.

Example:
```js
// prefer

_.merge(object1, object2);

// over

angular.extend(object1, object2);
```