Merge branch 'update-sassc' into 'master'

Update sassc gem 2.0.1 -> 2.2.1

See merge request gitlab-org/gitlab!27267

Gemfile.lock

@@ -973,9 +973,8 @@ GEM
     sass-listen (4.0.0)
       rb-fsevent (~> 0.9, >= 0.9.4)
       rb-inotify (~> 0.9, >= 0.9.7)
-    sassc (2.0.1)
+    sassc (2.2.1)
       ffi (~> 1.9)
-      rake
     sassc-rails (2.1.0)
       railties (>= 4.0.0)
       sassc (>= 2.0)