Replace gitter with discord (#210)

Going to use discord as the primary instant communication channel instead of gitter. Rearranged badges a little so that code quality related badges are on their own line.

README.md

@@ -2,13 +2,14 @@
 
 [![Release](https://img.shields.io/github/release/natlas/natlas.svg)](https://github.com/natlas/natlas/releases/latest)
 ![Last Commit](https://img.shields.io/github/last-commit/natlas/natlas.svg)
-[![Maintainability](https://api.codeclimate.com/v1/badges/321141e5cf7426874cd7/maintainability)](https://codeclimate.com/github/natlas/natlas/maintainability)
-[![Total alerts](https://img.shields.io/lgtm/alerts/g/natlas/natlas.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/natlas/natlas/alerts/)
 ![Total Downloads](https://img.shields.io/github/downloads/natlas/natlas/total.svg)
 ![Code Size](https://img.shields.io/github/languages/code-size/natlas/natlas.svg)
 [![Contributors](https://img.shields.io/github/contributors/natlas/natlas.svg)](https://github.com/natlas/natlas/graphs/contributors)
 [![License](https://img.shields.io/badge/license-Apache%202-blue.svg?style=flat)](LICENSE)
-[![Gitter chat](https://badges.gitter.im/gitterHQ/gitter.png)](https://gitter.im/natlasio)
+[![Discord](https://img.shields.io/discord/638428906612850709?label=discord)](https://discord.gg/VMbyMMT)
+
+[![Maintainability](https://api.codeclimate.com/v1/badges/321141e5cf7426874cd7/maintainability)](https://codeclimate.com/github/natlas/natlas/maintainability)
+[![Total alerts](https://img.shields.io/lgtm/alerts/g/natlas/natlas.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/natlas/natlas/alerts/)
 
 # Summary