adding ci badge, new screenshot

Author: alexandercbooth

README.md

@@ -1,17 +1,25 @@
 # create-nteract-app
 
+[![CircleCI](https://circleci.com/gh/nteract/create-nteract-app/tree/master.svg?style=svg)](https://circleci.com/gh/nteract/create-nteract-app/tree/master)
+
 ## Installation
+
 Install `create-nteract-app` globally
+
 ```bash
 npm i -g create-nteract-app
 ```
+
 ## Usage
+
 Create an nteract app and run the development server.
+
 ```bash
 create-nteract-app yourApp
 cd yourApp
 yarn dev
 ```
+
 Now, navigate to [here](http://localhost:3000/) and you should see the following:
 
-![](Screenshot.png)
+![](Screenshot.png)