Remove nitrous reference from readme

README.md

@@ -24,14 +24,6 @@ $ gem install bundler # If you don't have bundler installed
 $ bundle install
 ```
 
-If you don't want to install anything in your local machine, you can create a free development environment for this Pixyll project in the cloud on [Nitrous.io](https://www.nitrous.io) by clicking the button below.
-
-<a href="https://www.nitrous.io/quickstart">
-  <img src="https://nitrous-image-icons.s3.amazonaws.com/quickstart.png" alt="Nitrous Quickstart" width=142 height=34>
-</a>
-
-In the IDE, start Pixyll via `Run > Start Pixyll` and access your site via `Preview > 3000`.
-
 #### Verify your Jekyll version
 
 It's important to also check your version of Jekyll since this project uses Native Sass which