Update README.md

Added:
* [Get Your Hands Dirty Refactoring in AngularJS] (http://blog.safaribooksonline.com/2014/04/08/refactoring-angularjs-get-hands-filthy/)
* [Writing Tests and Stomping Bugs in AngularJS] (http://blog.safaribooksonline.com/2014/04/01/writing-tests-stomping-bugs-angularjs/)