Upgrade to livingstyleguide v2 syntax

Signed-off-by: Alex Coles <alex@alexbcoles.com>

app/assets/stylesheets/open_project_global/_variables.lsg

@@ -4,9 +4,9 @@ Color Variables
 ## Global Color Variables
 
 ```
-@colors
-- $body-font-color -
-- $primary-color $primary-color-dark
-- $alternative-color -
-$gray-light $gray $gray-dark
+@colors {
+- $body-font-color - -
+- $header-bg-color - $header-logo-bg-color -
+- $gray-light $gray $gray-dark
+}
 ```

app/assets/stylesheets/styleguide.html.lsg

@@ -1,14 +1,15 @@
-# Base setup:
-source: ../stylesheets/default.css.sass
-title: "Living Style Guide for OpenProject"
+@require sass
 
-# Adjust default LivingStyleGuide design:
-style:
-  base-font: Lato
-  base-font-size: 16px
-  background-color: white
+@css ../stylesheets/default.css.sass
+@title "Living Style Guide for OpenProject"
 
-styleguide-sass: |
+@style base-font: Lato
+@style base-font-size: 16px
+@style background-color: white
+
+@default preprocessor: sass
+
+@css
   .livingstyleguide--header
     @include grid-content
 
@@ -39,10 +40,7 @@ styleguide-sass: |
   .livingstyleguide--example
     overflow: visible
 
-javascript-before:
-  - "/assets/styleguide.js"
-
-header: |
+@header
   <header class="livingstyleguide--header">
     <div class="styleguide-banner">
       <h1 class="styleguide-banner--text">Living Style Guide</h1>
@@ -67,7 +65,11 @@ header: |
     <p>&nbsp;</p>
   </section>
 
-footer: |
+@javascript-before /assets/styleguide.js
+
+@footer
   <footer class="livingstyleguide--footer">
     Copyright © 2015 OpenProject - All rights reserved.
   </footer>
+
+@import ../stylesheets/**/_*.lsg