Re-introduce Ruby

fixes #8, #9, #10, #11
- Add Gemfile
- Swap normalize.css with normalize-scss
- Add grunt-contrib-sass task to compile sass
- Ignore .sass-cache

Gemfile

@@ -0,0 +1,5 @@
+source 'https://rubygems.org'
+
+gem 'bourbon', "~> 3.1.8"
+gem "sass", "~> 3.3.1"
+

Gemfile.lock

@@ -0,0 +1,15 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    bourbon (3.1.8)
+      sass (>= 3.2.0)
+      thor
+    sass (3.3.1)
+    thor (0.18.1)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  bourbon (~> 3.1.8)
+  sass (~> 3.3.1)

core/client/assets/sass/screen.scss

@@ -10,7 +10,7 @@
 @import "modules/mixins";
 /* Sass variables like colours, font sizes, basic styles. */
 
-@import "normalize.css";
+@import "normalize";
 /* Browser cross compatibility normalisation*/
 
 @import "modules/icons";