Rewrite to idiomatic Redux

[gaearon]

This rewrites the Redux example to a more idiomatic way. Changes:

• Adds logger in development
• The state is normalized
• More reducer composition is used
• More queries are defined alongside reducers
• Tracking the IDs put into cart or displayed after fetch is explicit—closer to real apps
• The products are no longer passed into actions because the data in state is sufficient
• There is a rollback for failure
• There is a check to prevent ordering an out-of-stock item (just in case)
• Unnecessary connect() calls are removed
• Unnecessary component is removed
• Instead of manually calling bindActionCreators we let React Redux do the binding