Merge pull request #5 from xlu/item-image-url

Add item.image_url feature.
Stub out HTTParty calls
Bump to version 0.0.2
Add webmock to not allow actual calls
Take both symbol and string keys for params
Bump version
Manual merge with master

Merge branch 'master' into order_params

Conflicts:
	lib/walmart_open/shipping_address.rb
	spec/walmart_open/order_spec.rb
	spec/walmart_open/shipping_address_spec.rb