Properly disable http pipelining

It's causing memory corruption issues along with image optimization.
Rel: #633

lib/docs/core/requester.rb

@@ -20,7 +20,7 @@ module Docs
     def initialize(options = {})
       @request_options = options.extract!(:request_options)[:request_options].try(:dup) || {}
       options[:max_concurrency] ||= 20
-      options[:pipelining] = 0
+      options[:pipelining] = false
       super
     end