update readme

README.md

@@ -17,9 +17,8 @@ $ wdm update --standalone // install selenium and webdrivers
 Then install `viff` command line.
 
 ```
-npm install -g coffee-script && npm install -g viff
+npm install -g viff
 ```
-No need to install coffee-script if you already have it, of course.
 
 ## Examples
 
@@ -147,6 +146,8 @@ And integrated `viffclient.post` method in your functional testing code. Check m
 
 # History
 
+2014-08-07 **[email protected]** no need to install `coffee-script` before hand.
+
 2014-06-08 **[email protected]** could use multi viff instances to improve testing performance (`maxInstance` property).
 
 2014-05-18 **[email protected]** finally replace `canvas` by `phantomjs`, so easy installation starts from now, even in Windows System.