Update SASS pipeline to generate source maps

Note: this requires SASS 3.3+ so do ```bundle install```

Gemfile

 source 'https://rubygems.org'
 gem 'rake', '~> 10.0.3'
-gem 'sass', '3.2.12'
+gem 'sass', '3.3.5'
 gem 'bourbon', '~> 3.1.8'
 gem 'neat', '~> 1.4.0'
 gem 'colorize', '~> 0.5.8'

Gemfile.lock

@@ -33,5 +33,5 @@ DEPENDENCIES
   rake (~> 10.0.3)
   rb-fsevent (~> 0.9.3)
   rb-inotify (~> 0.9)
-  sass (= 3.2.12)
+  sass (= 3.3.5)
   sys-proctable (~> 0.9.3)

pavelib/assets.py

@@ -130,9 +130,10 @@ def compile_sass(debug=False):
     """
     sh(cmd(
         'sass', '' if debug else '--style compressed',
+        "--sourcemap",
         "--cache-location {cache}".format(cache=SASS_CACHE_PATH),
         "--load-path", " ".join(SASS_LOAD_PATHS + THEME_SASS_PATHS),
-        "--update", "-E", "utf-8", " ".join(SASS_UPDATE_DIRS + THEME_SASS_PATHS)
+        "--update", "-E", "utf-8", " ".join(SASS_UPDATE_DIRS + THEME_SASS_PATHS),
     ))