README.md in cello-0.0.34 vs README.md in cello-0.0.35

@@ -53,9 +53,11 @@
 
 Developing
 ----------
 To develop `cello`, you are going to need [Bundler][1] 
 
+You need to have phantomjs installed to run the tests: http://phantomjs.org/ 
+
     $ git clone [e-mail]:camiloribeiro/cello.git
     $ cd cello
     $ bundle install
     $ rake