Remove Final Travis CI Pieces (#55)

* Update build badge in README

* Remove unneeded .travis.yml file

* Remove gitter in favor of GitHub issues

README.md

@@ -1,8 +1,7 @@
 # Runbook
 
 [![Gem Version](https://badge.fury.io/rb/runbook.svg)](https://badge.fury.io/rb/runbook)
-[![Build Status](https://travis-ci.org/braintree/runbook.svg?branch=master)](https://travis-ci.org/braintree/runbook)
-[![Gitter](https://badges.gitter.im/braintree/runbook.svg)](https://gitter.im/braintree/runbook?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge)
+[![Build Status](https://github.com/braintree/runbook/actions/workflows/ruby.yml/badge.svg?branch=master&event=push)](https://github.com/braintree/runbook/actions?query=branch%3Amaster+event%3Apush)
 
 _See our [blog post](https://medium.com/braintree-product-technology/https-medium-com-braintree-product-technology-runbook-be6f072cfc0d) for the philosophy behind Runbook and an overview of its features._