Update dependencies to their latest versions

Makefile

@@ -2,7 +2,7 @@ sass:
 	@grunt sass
 
 install:
-	@gem install sass --no-ri --no-rdoc
+	@npm install sass grunt -g
 	@npm install
 
 run:

README.md

@@ -4,20 +4,23 @@ This is the [tsuru.io](http://tsuru.io) landing page.
 
 ## Setting up
 
-You must have [SASS](http://sass-lang.com/), [Node.js](https://nodejs.org/) and [grunt-cli](http://gruntjs.com/getting-started) installed.
+You must have the latest [Node.js](https://nodejs.org/) version installed.
+
 After that, clone this project:
 
 ```shell
 $ git clone [email protected]:tsuru/tsuru.io.git
 ```
 
-And install the dependencies:
+Then install the dependencies:
 
 ```shell
 $ cd tsuru.io
 $ make install
 ```
 
+This will install [SASS](http://sass-lang.com/) and [Grunt](http://gruntjs.com/getting-started) CLIs globally in your computer.
+
 That's it. You're set.
 
 ## Running & developing

grunt-tasks/sass.coffee

@@ -1,7 +1,6 @@
 module.exports = (grunt) ->
   grunt.config 'sass',
     options:
-      sourcemap: 'none'
       style: 'compressed'
     dist:
       files: [