[dev_setup] Cache ruby tarballs

Ruby source tarballs are now cached to speed up repeated
installations.
  Test plan: run dev_setup without cache, with cache, and with a
corrupted cached tarball.

Change-Id: I3bd5e089d60ac9b51193f80efffa916d63fdba36

dev_setup/cookbooks/ruby/attributes/default.rb

@@ -2,6 +2,7 @@ include_attribute "deployment"
 default[:ruby][:version] = "1.9.2-p180"
 default[:ruby][:source]  = "http://ftp.ruby-lang.org//pub/ruby/1.9/ruby-#{ruby[:version]}.tar.gz"
 default[:ruby][:path]    = File.join(node[:deployment][:home], "deploy", "rubies", "ruby-#{ruby[:version]}")
+default[:ruby][:checksums]["1.9.2-p180"] = "9027a5abaaadc2af85005ed74aeb628ce2326441874bf3d4f1a842663cde04f4"
 
 default[:rubygems][:version] = "1.8.7"
 default[:rubygems][:bundler][:version] = "1.0.18"

dev_setup/cookbooks/ruby/attributes/ruby18.rb

@@ -2,3 +2,4 @@ include_attribute "deployment"
 default[:ruby18][:version] = "1.8.7-p334"
 default[:ruby18][:source]  = "http://ftp.ruby-lang.org//pub/ruby/1.8/ruby-#{ruby18[:version]}.tar.gz"
 default[:ruby18][:path]    = File.join(node[:deployment][:home], "deploy", "rubies", "ruby-#{ruby18[:version]}")
+default[:ruby][:checksums]["1.8.7-p334"] = "68f68d6480955045661fab3be614c504bfcac167d070c6fdbfc9dbe2c5444bc0"

dev_setup/cookbooks/ruby/libraries/ruby_install.rb

@@ -8,10 +8,10 @@ module RubyInstall
       package pkg
     end
 
-    remote_file File.join("", "tmp", "ruby-#{ruby_version}.tar.gz") do
+    remote_file File.join(node[:deployment][:setup_cache], "ruby-#{ruby_version}.tar.gz") do
       owner node[:deployment][:user]
       source ruby_source
-      not_if { ::File.exists?(File.join("", "tmp", "ruby-#{ruby_version}.tar.gz")) }
+      checksum node[:ruby][:checksums][ruby_version]
     end
 
     directory ruby_path do