Refactor API classes. So api classes like Gitlab::Issues become API::Issues

spec/requests/api/notes_spec.rb

 require 'spec_helper'
-describe Gitlab::API do
+describe API::API do
   include ApiHelpers
   let(:user) { create(:user) }

spec/requests/api/projects_spec.rb

 require 'spec_helper'
-describe Gitlab::API do
+describe API::API do
   include ApiHelpers
   before(:each) { enable_observers }

spec/requests/api/session_spec.rb

 require 'spec_helper'
-describe Gitlab::API do
+describe API::API do
   include ApiHelpers
   let(:user) { create(:user) }

spec/requests/api/system_hooks_spec.rb

 require 'spec_helper'
-describe Gitlab::API do
+describe API::API do
   include ApiHelpers
   let(:user) { create(:user) }

spec/requests/api/users_spec.rb

 require 'spec_helper'
-describe Gitlab::API do
+describe API::API do
   include ApiHelpers
   let(:user)  { create(:user) }

spec/routing/routing_spec.rb

@@ -7,7 +7,7 @@ describe SearchController, "routing" do
   end
 end
-# gitlab_api /api         Gitlab::API
+# gitlab_api /api         API::API
 #     resque /info/resque Resque::Server
 #            /:path       Grack
 describe "Mounted Apps", "routing" do

spec/support/api_helpers.rb

@@ -18,7 +18,7 @@ module ApiHelpers
   #
   # Returns the relative path to the requested API resource
   def api(path, user = nil)
-    "/api/#{Gitlab::API.version}#{path}" +
+    "/api/#{API::API.version}#{path}" +
       # Normalize query string
       (path.index('?') ? '' : '?') +