Update README to use SVG for Travis Icon [ci skip]

README.md

@@ -2,7 +2,7 @@
   <img src="https://raw.github.com/AFNetworking/AFNetworking/assets/afnetworking-logo.png" alt="AFNetworking" title="AFNetworking">
 </p>
 
-[![Build Status](https://travis-ci.org/AFNetworking/AFNetworking.png)](https://travis-ci.org/AFNetworking/AFNetworking)
+[![Build Status](https://travis-ci.org/AFNetworking/AFNetworking.svg)](https://travis-ci.org/AFNetworking/AFNetworking)
 
 AFNetworking is a delightful networking library for iOS and Mac OS X. It's built on top of the [Foundation URL Loading System](http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/URLLoadingSystem/URLLoadingSystem.html), extending the powerful high-level networking abstractions built into Cocoa. It has a modular architecture with well-designed, feature-rich APIs that are a joy to use.