Remove reference to localeapp from i18n guide

Fixes #199
Document other approach to extend attribute in api json templates
Fix example in custom_attributes guide
Add documentation for the shipment states

Fixes #200
Remove attr_accessible in 'Custom Attributes' guide

Fixes #198
Update products + variants API examples for Spree 2.1
Attributes in Variant API examples should be shown before associations

Conflicts:
	lib/resources.rb
Remove count_on_hand from variants results
Update adjustments guide for Spree 2.2.