Docs: Update Travis badge

Migrated from deprecated Travis CI dot-org and deprecated GitHub service hooks,
to dot-com via GitHub Apps integration.

Closes #1380.

Author: Krinkle

README.md

@@ -1,4 +1,4 @@
-[![Build Status](https://travis-ci.org/qunitjs/qunit.svg?branch=master)](https://travis-ci.org/qunitjs/qunit)
+[![Build Status](https://travis-ci.com/qunitjs/qunit.svg?branch=master)](https://travis-ci.com/qunitjs/qunit)
 [![Coverage Status](https://coveralls.io/repos/qunitjs/qunit/badge.svg)](https://coveralls.io/github/qunitjs/qunit)
 [![Chat on Gitter](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/qunitjs/qunit?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 [![FOSSA Status](https://app.fossa.io/api/projects/git%2Bhttps%3A%2F%2Fgithub.com%2Fqunitjs%2Fqunit.svg?type=shield)](https://app.fossa.io/projects/git%2Bhttps%3A%2F%2Fgithub.com%2Fqunitjs%2Fqunit?ref=badge_shield)