Dynamically fetch assets in twig templates

**Previously assets were fetched like this:**
* For stylesheets - `<link rel="stylesheet" href="/assets/v4/css/style.css" />`
* For Scripts - `<script src="/assets/vendor/jquery-2.1.0.min.js"></script>`
* For Images - `<img src="/assets/v4/img/vendors/python-active.png" />`

**But now they will be feteched dynamically like this:**
* For stylesheets - `<link rel="stylesheet" href="{{ asset('assets/v4/css/style.css') }}" />`
* For Scripts - `<script src="{{ asset('assets/vendor/jquery-2.1.0.min.js') }}"></script>`
* For Images - `<img src="{{ asset('assets/v4/img/vendors/python-active.png') }}" />`