Introducing rem mixin and function

This mixin come in handy for the news container to make it scalable depending on the users choice of text size in their browsers.

Usage:

```scss
    @include rem((
        padding: 20px,
        width: 300px,
        height: 350px,
        line-height: 20px
    ));
```

![ ](http://i.imgur.com/pCYonBW.gif)