* New CSS component – Dropdown menu
 * Currently fully supported only when placed within `ul.navigation`
 * Mobile friendly mode supported
 * No support for nested dropdown menus
* Implemented dropdown support code in `butterfly.js`
* Added `scss/_menu.scss` to the project
* Implemented CSS for applying styled border to `img` elements by adding `.border` class to them
* Added an option of disabling navigation responsiveness by adding `.navigation-desktop` class to the `ul.navigation` tag