Update README file to use new travis.com domain

Author: boriel

README.md

@@ -1,6 +1,6 @@
 ![Boriel ZX Basic](img/zxbasic_logo.png)
 
-[![Build Status](https://travis-ci.org/boriel/zxbasic.svg?branch=master)](https://travis-ci.org/boriel/zxbasic)
+[![Build Status](https://travis-ci.com/boriel/zxbasic.svg?branch=master)](https://travis-ci.org/boriel/zxbasic)
 [![license](https://img.shields.io/badge/License-GPLv3-blue.svg)](./LICENSE.txt)
 [![pyversions](https://img.shields.io/pypi/pyversions/zxbasic.svg)](https://pypi.python.org/pypi/zxbasic)