Switch to sassc-rails for faster SASS compilation

Gemfile

@@ -34,8 +34,6 @@ gem 'argon2'
 # performance - Memcached
 gem 'dalli'
 
-# asset handling
-group :assets do
 # asset handling - coffee-script
 gem 'coffee-rails'
 gem 'coffee-script-source'
@@ -44,12 +42,11 @@ group :assets do
 gem 'eco'
 
 # asset handling - SASS
-  gem 'sass-rails'
+gem 'sassc-rails'
 
 # asset handling - pipeline
 gem 'sprockets'
 gem 'uglifier'
-end
 
 gem 'autoprefixer-rails'
 

Gemfile.lock

@@ -395,17 +395,15 @@ GEM
     ruby_dep (1.5.0)
     rubyzip (1.2.2)
     safe_yaml (1.0.4)
-    sass (3.5.3)
-      sass-listen (~> 4.0.0)
-    sass-listen (4.0.0)
-      rb-fsevent (~> 0.9, >= 0.9.4)
-      rb-inotify (~> 0.9, >= 0.9.7)
-    sass-rails (5.0.7)
-      railties (>= 4.0.0, < 6)
-      sass (~> 3.1)
-      sprockets (>= 2.8, < 4.0)
-      sprockets-rails (>= 2.0, < 4.0)
-      tilt (>= 1.1, < 3)
+    sassc (2.0.0)
+      ffi (~> 1.9.6)
+      rake
+    sassc-rails (2.0.0)
+      railties (>= 4.0.0)
+      sassc (>= 2.0)
+      sprockets (> 3.0)
+      sprockets-rails
+      tilt
     sawyer (0.8.1)
       addressable (>= 2.3.5, < 2.6)
       faraday (~> 0.8, < 1.0)
@@ -570,7 +568,7 @@ DEPENDENCIES
   rspec-rails
   rubocop
   rubyntlm!
-  sass-rails
+  sassc-rails
   selenium-webdriver
   simplecov
   simplecov-rcov