Update readme styling

README.md

-Slate
-========
+<p align="center">
+  <img src="https://raw.githubusercontent.com/lord/img/master/logo-slate.png" alt="Slate: API Documentation Generator" width="226">
+  <br>
+  <a href="https://travis-ci.org/tripit/slate"><img src="https://travis-ci.org/tripit/slate.svg?branch=master" alt="Build Status"></a>
+</p>
+
 
 [![Build Status](https://travis-ci.org/tripit/slate.svg?branch=master)](https://travis-ci.org/tripit/slate) [![Dependency Status](https://gemnasium.com/tripit/slate.png)](https://gemnasium.com/tripit/slate)
 
-Slate helps you create beautiful API documentation. Think of it as an intelligent, responsive documentation template for your API.
+<p align="center">Slate helps you create beautiful, intelligent, responsive API documentation.</p>
 
-<img src="https://dl.dropboxusercontent.com/u/95847291/github%20images/slate/slate_screenshot_new.png" width=700 alt="Screenshot of Example Documentation created with Slate">
+<p align="center"><img src="https://dl.dropboxusercontent.com/u/95847291/github%20images/slate/slate_screenshot_new.png" width=700 alt="Screenshot of Example Documentation created with Slate"></p>
 
-*The example above was created with Slate. Check it out at [tripit.github.io/slate](http://tripit.github.io/slate).*
+<p align="center"><em>The example above was created with Slate. Check it out at <a href="https://tripit.github.io/slate">tripit.github.io/slate</a>.</em></p>
 
 Features
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