Add about sections

* Add about SaferNYC and about the data sections
* Add links to view about sections as pop-ups
* Add JavaScript to enable pop-ups
* Style links and about sections
* Make HTML, JS code improvements
you can do the 

```html
<p>
   Lorem ipsum dolor sit amet, consectetur adipiscing elit. 
   Donec a diam lectus. Sed sit amet ipsum mauris. Maecenas 
   congue ligula ac quam viverra nec consectetur ante hendrerit. 
   Donec et mollis dolor. Praesent et diam eget libero egestas 
   mattis sit amet vitae augue. Nam tincidunt congue enim, 
   ut porta lorem lacinia consectetur. Donec ut libero sed arcu 
   vehicula ultricies a non tortor. Lorem ipsum dolor sit amet,
   consectetur adipiscing elit. Aenean ut gravida lorem. Ut 
   turpis felis, pulvinar a semper sed, adipiscing id dolor. 
</p>
```