Add creating with line items example
Show where a failure occurred
Add order importing example
Add an example of adding a user to an order

This requires the absolute latest commits to 2-2-stable/master.

These will be available on spree/spree proper later in the week.

Fixes #1
Fixes for 2-3
Add in test for 4927
Remove comments regarding the payment attributes
Add message reporting for spree/spree#4927
Add JSON examples.
Delete files.
Allow examples to be run by any particular client, as long as it matches an API
Use client methods instead of puts in products/listing
Add Braintree token-based example
Merge branch '2-3-stable'

Conflicts:
	examples/checkout/creating_with_line_items.rb
	examples/checkout/walkthrough.rb
	examples/client.rb
	examples/orders/importing.rb
Add exmaple