Update CONTRIBUTING.md

Replace cefbuilds link with spotify

CONTRIBUTING.md

@@ -42,7 +42,7 @@ Your bug report should **always follow this template**:
     - A stack trace if available, any Exception information.
     - Does the cef log provide any relevant information? (By default there should be a debug.log file in your bin directory)
 - Any other background information that's relevant? Are you doing something out of the ordinary? 3rd party controls?
-- **Does this problem also occur in the `Cef` TestApp from http://cefbuilds.com?**
+- **Does this problem also occur in the `CEF Sample Application` from http://opensource.spotify.com/cefbuilds/index.html?**
 
 Your bug report should include **what you were doing** in the software when you encountered it, **what you were expecting** to happen and **what happened instead**.