Revert "Enable HTTP client caching."

This reverts commit 7bc6977.

Cache needs a dedidcated backing store to be effective across runs,
defer it now.

Author: mostlyobvious

lib/nanoc/github.rb

@@ -9,14 +9,6 @@ module Github
     class Source < Nanoc::DataSource
       identifier :github
 
-      def up
-        Octokit.middleware = Faraday::RackBuilder.new do |builder|
-          builder.use Faraday::HttpCache, serializer: Marshal, shared_cache: false
-          builder.use Octokit::Response::RaiseError
-          builder.adapter Faraday.default_adapter
-        end
-      end
-
       def items
         @items ||= begin
           repository_items.map do |item|