Fix tests of 01-Ruby / 04-Hash-Symbols / Optional-03-Shopping-Cart
Update exercise README
Merge pull request #24 from lewagon/01-Ruby/04-Hash-Symbols/Optional-03-Shopping-Cart

Fix tests of 01-Ruby / 04-Hash-Symbols / Optional-03-Shopping-Cart
Cookbook refactored
Merge pull request #25 from lewagon/cookbook-refactored

Cookbook refactored
solved conflict