Create ScrollNavigation.js

Started with:
$('nav a').ScrollNavigation();
Where 'nav a', is the navigation elements that we search for.
The default settings are these:
{
  sections: '#content section', // containers
  throttle: 250, // ms to throttle the function
  margin: 50, // px margin, this is margin from the top before section is set to active,
  activeClass: 'selected' // active class set on the anchor
}