Update rack-cors to ~> 0.4.0

Gemfile

@@ -65,9 +65,9 @@ gem 'gollum-lib', '~> 4.0.2'
 gem "gitlab-linguist", "~> 3.0.1", require: "linguist"
 
 # API
-gem "grape", "~> 0.6.1"
-gem "grape-entity", "~> 0.4.2"
-gem 'rack-cors', '~> 0.2.9', require: 'rack/cors'
+gem 'grape',        '~> 0.6.1'
+gem 'grape-entity', '~> 0.4.2'
+gem 'rack-cors',    '~> 0.4.0', require: 'rack/cors'
 
 # Format dates and times
 # based on human-friendly examples

Gemfile.lock

@@ -496,7 +496,7 @@ GEM
       rack (>= 0.4)
     rack-attack (4.3.0)
       rack
-    rack-cors (0.2.9)
+    rack-cors (0.4.0)
     rack-mini-profiler (0.9.7)
       rack (>= 1.1.3)
     rack-mount (0.8.3)
@@ -883,7 +883,7 @@ DEPENDENCIES
   pry-rails
   quiet_assets (~> 1.0.2)
   rack-attack (~> 4.3.0)
-  rack-cors (~> 0.2.9)
+  rack-cors (~> 0.4.0)
   rack-mini-profiler (~> 0.9.0)
   rack-oauth2 (~> 1.0.5)
   rails (= 4.1.12)