Fix capitalisation in travis link.

Author: judgej

README.md

@@ -1,5 +1,5 @@
 
-[![Build Status](https://travis-ci.org/academe/Omnipay-AuthorizeNetApi.svg?branch=master)](https://travis-ci.org/academe/Omnipay-AuthorizeNetApi)
+[![Build Status](https://travis-ci.org/academe/omnipay-authorizenetapi.svg?branch=master)](https://travis-ci.org/academe/omnipay-authorizenetapi)
 [![Latest Stable Version](https://poser.pugx.org/academe/omnipay-authorizenetapi/v/stable)](https://packagist.org/packages/academe/omnipay-authorizenetapi)
 [![Total Downloads](https://poser.pugx.org/academe/omnipay-authorizenetapi/downloads)](https://packagist.org/packages/academe/omnipay-authorizenetapi)
 [![Latest Unstable Version](https://poser.pugx.org/academe/omnipay-authorizenetapi/v/unstable)](https://packagist.org/packages/academe/omnipay-authorizenetapi)