Lock sass-rails to >= 4.0.3

Gemfile

@@ -19,7 +19,7 @@ platforms :ruby_18 do
 end
 
 group :assets do
-  gem 'sass-rails'
+  gem 'sass-rails', '>= 4.0.3'
   gem 'uglifier'
 end
 

Gemfile.lock

@@ -153,11 +153,12 @@ GEM
       ruby-progressbar (~> 1.4)
     ruby-progressbar (1.4.2)
     safe_yaml (1.0.2)
-    sass (3.3.4)
-    sass-rails (4.0.1)
+    sass (3.2.19)
+    sass-rails (4.0.3)
       railties (>= 4.0.0, < 5.0)
-      sass (>= 3.1.10)
-      sprockets-rails (~> 2.0.0)
+      sass (~> 3.2.0)
+      sprockets (~> 2.8, <= 2.11.0)
+      sprockets-rails (~> 2.0)
     simplecov (0.8.2)
       docile (~> 1.1.0)
       multi_json
@@ -170,7 +171,7 @@ GEM
       multi_json (~> 1.0)
       rack (~> 1.0)
       tilt (~> 1.1, != 1.3.0)
-    sprockets-rails (2.0.1)
+    sprockets-rails (2.1.1)
       actionpack (>= 3.0)
       activesupport (>= 3.0)
       sprockets (~> 2.8)
@@ -216,7 +217,7 @@ DEPENDENCIES
   rails_12factor
   rails_admin
   rubocop
-  sass-rails
+  sass-rails (>= 4.0.3)
   simplecov
   spring
   sqlite3