Sprite error

Now, when using sprites, I've got this error:

```shel
λ jekyll build --trace
Configuration file: C:/wrks/git/kelvinst.github.io/_config.yml
            Source: C:/wrks/git/kelvinst.github.io
       Destination: C:/wrks/git/kelvinst.github.io/_site
      Generating...
   create images/icons-sbcaf79b2e7.png
   remove images/icons-sbcaf79b2e7.png
C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/jekyll-compass-0.1.0/lib/jekyll/compass.rb:57:in `block (2 levels) in generate': undefined method `sprite_output' for #<Jekyll::Compass:0x4acdcd8> (NoMethodError)
        from C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/jekyll-compass-0.1.0/lib/jekyll/compass.rb:55:in `select'
        from C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/jekyll-compass-0.1.0/lib/jekyll/compass.rb:55:in `block in generate'
        from C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/sass-3.2.12/lib/sass/callbacks.rb:60:in `[]'
        from C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/sass-3.2.12/lib/sass/callbacks.rb:60:in `block in run_sprite_removed'
        ...
```

So, I fixed it...