Do not vendor cookbooks using Berkshelf anymore

Instead, use the Berkshelf support in knife-solo and the
vagrant-berkshelf plugin on Vagrant

cookbooks/redis/spec/spec_helper.rb

@@ -1,20 +0,0 @@
-begin
-  require "chefspec"
-  require "chefspec/berkshelf"
-rescue LoadError
-  puts "Unable to run `chefspec`"
-  exit
-end
-
-RSpec.configure do |config|
-  config.platform = "ubuntu"
-  config.version = "12.04"
-  config.log_level = :error
-  config.raise_errors_for_deprecations!
-end
-
-def add_apt_repository(resource_name)
-  ChefSpec::Matchers::ResourceMatcher.new(:apt_repository, :add, resource_name)
-end
-
-at_exit { ChefSpec::Coverage.report! }