Add badges to README

README.md

@@ -1,3 +1,10 @@
+<p align="center">
+  <a href="https://goreportcard.com/report/github.com/fyne-io/pixeledit"><img src="https://goreportcard.com/badge/github.com/fyne-io/pixeledit" alt="Code Status" /></a>
+  <a href="https://travis-ci.org/fyne-io/pixeledit"><img src="https://travis-ci.org/fyne-io/pixeledit.svg" alt="Build Status" /></a>
+  <a href='https://coveralls.io/github/fyne-io/pixeledit?branch=master'><img src='https://coveralls.io/repos/github/fyne-io/pixeledit/badge.svg?branch=master' alt='Coverage Status' /></a>
+  <a href='http://gophers.slack.com/messages/fyne'><img src='https://img.shields.io/badge/join-us%20on%20slack-gray.svg?longCache=true&logo=slack&colorB=blue' alt='Join us on Slack' /></a>
+</p>
+
 # Pixel Editor
 
 A pixel based image editor built using Fyne.