Add example for gateway payment profile id
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
Update README.md
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
Cleanup merge conflict