Merge pull request #3 from sergelerator/master

Updated the README and added the Taxon Model
Saving the order object after fetching it from the remote source
LineItem model and API for adding items to cart
Integrating the newly added LineItem model and API
Merge pull request #4 from sergelerator/create_line_items

Create line items
Refactored line_items_request to create_line_item_request
Added line_items attribute to the fetched order
Fixed a bug in LineItem#create_line_item
Changed how Order.fetch! invokes a given block
Spree.update_line_item and Spree.delete_line_item, check
Changed the update_line_item API call to put when no block is given
Fixed a typo in a method call
OrderModel#refresh retrieves the order from the endpoint
Added sign_out! method to Auth class
Merge pull request #5 from sergelerator/create_line_items

Spree.update_line_item and Spree.delete_line_item, check
Merge pull request #6 from sergelerator/sign_out

Added sign_out! method to Auth class