Merge branch '1141-repo-size-error-refactor' into 'master'

Reduce code included in `RepositorySizeError`

Closes #1141

See merge request !833

lib/gitlab/repository_size_error.rb

 module Gitlab
   class RepositorySizeError
-    include ActionView::Helpers
+    include ActiveSupport::NumberHelper
 
     attr_reader :project