Navigation Enhancements with ID's and URL hashes

### Important Note
This does not break ANY current functionality. It simply provides users additional options for using your framework.

Summary
========
Allow users to link directly to ID's of slides instead of specifying an additional `data-slide` attribute on each.

Also update the URL hash when navigating to slides with IDs. This allows for sharing of specific locations on the page after navigating.

Example
-----------
A nav element like this
```
<li data-slide="about">About</li>
```
Would link directly to a div like this.
```
<div class="slide" id="about">This is my about section</div>
```

This is more semantic as we are describing the content we are linking to rather than assigning it an arbitrary number. 

URL Hash Updating
----------------------------
When navigating to a location on the page, the URL hash will also update to the ID of the slide being navigated to. Using the example above, the URL would be updated to 
```
www.example.com/mypage.html#about
```
 which will allow anyone sharing content from the page to direct the recipient to a specific location on a page.