Add SASS / SCSS support. Closes #1.

src/languages/index.coffee

@@ -4,13 +4,14 @@
 {EcoLanguage} = require './eco'
 {JadeLanguage} = require './jade'
 {JavaScriptLanguage} = require './javascript'
+{HoganLanguage} = require './hogan'
 {LESSLanguage} = require './less'
 {RoyLanguage} = require './roy'
+{SassLanguage} = require './sass'
 {StylusLanguage} = require './stylus'
-{HoganJsLanguage} = require './hogan'
 
 module.exports = {
   BaseLanguage, CoffeeScriptLanguage, CSSLanguage, EcoLanguage,
-  JadeLanguage, JavaScriptLanguage, LESSLanguage, RoyLanguage,
-  StylusLanguage, HoganJsLanguage
+  JadeLanguage, JavaScriptLanguage, HoganLanguage,
+  LESSLanguage, RoyLanguage, SassLanguage, StylusLanguage
 }

src/languages/sass.coffee

@@ -0,0 +1,23 @@
+{spawn} = require 'child_process'
+{BaseLanguage} = require './base'
+
+class exports.SassLanguage extends BaseLanguage
+  compile: (file, callback) ->
+    @readFile file, (error, data) =>
+      return callback error if error?
+      result = ''
+      error = null
+      # Warning: spawning child processes is a quite slow operation.
+      # On my machine, it's ~200ms, when compiling stylus via node.js
+      # without spawning child process is ~20ms.
+      options = [
+        '--stdin',
+        '--load-path', (@getRootPath 'app', 'styles'),
+        '--no-cache',
+      ]
+      options.push '--scss' if /\.scss$/.test file
+      sass = spawn 'sass', options
+      sass.stdin.end data
+      sass.stdout.on 'data', (data) -> result = data
+      sass.stderr.on 'data', (data) -> error = data
+      sass.on 'exit', (code) -> callback error, result.toString()

src/plugins/assets.coffee

@@ -1,5 +1,4 @@
 async = require 'async'
-mkdirp = require 'mkdirp'
 {ncp} = require 'ncp'
 path = require 'path'
 {BasePlugin} = require './base'