Add link to survey and input box for PIN
Add a class to pick random pairs from an underlying array

The namespace Picker::* seems to be more appropriate than Thing::*
namespace.
Add a sample file of animals to compare

List of items to compare consists of an item id and item description.
Add an in-memory server-side session for testing
Picker helper to seed list from an external file
Use string representation of GUID for session ID
Fix inadvertent extra indentation in IP helper
HTTP GET shows the alternatives.