Bump Sass to latest 3.4.x

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

Gemfile

@@ -95,7 +95,7 @@ gem 'sprockets',        git: 'https://github.com/tessi/sprockets.git', branch: '
 gem 'sprockets-rails',  git: 'https://github.com/finnlabs/sprockets-rails.git', branch: 'backport'
 gem 'non-stupid-digest-assets'
 gem 'sass-rails',        git: 'https://github.com/guilleiguaran/sass-rails.git', branch: 'backport'
-gem 'sass',             '~> 3.3.6'
+gem 'sass',             '~> 3.4.9'
 gem 'bourbon',          '~> 4.0'
 gem 'uglifier',         '>= 1.0.3', require: false
 gem 'livingstyleguide', '~> 1.2.0'

Gemfile.lock

@@ -349,7 +349,7 @@ GEM
       json (>= 1.7.5)
       structured_warnings (>= 0.1.3)
     rubyzip (1.1.6)
-    sass (3.3.14)
+    sass (3.4.9)
     selenium-webdriver (2.44.0)
       childprocess (~> 0.5)
       multi_json (~> 1.0)
@@ -479,7 +479,7 @@ DEPENDENCIES
   ruby-prof
   ruby-progressbar
   rubytree (~> 0.8.3)
-  sass (~> 3.3.6)
+  sass (~> 3.4.9)
   sass-rails!
   selenium-webdriver (~> 2.44.0)
   shoulda