FIX: #213 Deleting cart item view should not raise an error
In cart_modifiers methods ``get_extra_cart_price_field`` and ``get_extra_cart_item_price_field``
accepts the additional field ``state`` to pass customized data from ``Cart.update()``
down to these methods.
Fixes backwards compatibility issues where state was missing
Enable customized Order short name
Move impl. of short_name property to BaseOrder
Added a simple payment backend to be used for payments in advance, for instance wire transfer
Fixed string for transactionId
Merge pull request #221 from jrief/add-prepayment-backend

Added a simple payment backend to be used for payments in advance
Merge pull request #209 from atheiste/master

Uses new swappable user
Merge branch 'fix-213-deleting-cart-item' of https://github.com/bmihelac/django-shop into bmihelac-fix-213-deleting-cart-item

Conflicts:
	shop/views/cart.py
Merge branch 'master' of github.com:divio/django-shop
Drop support for Django 1.3.
Merge pull request #224 from anderspetersson/master

Drop support for Django 1.3
Added Anders to AUTHORS! Thanks a lot!
Merge pull request #220 from jacekmitrega/0.1.2-order-short-name

Enable customized Order short name
Added Jacek to AUTHORS. Thanks a lot!
Added safty check for callability of as_text() method
Merge branch 'master' into add-callable
Merge pull request #226 from jrief/add-callable

Add callable
Set order to status COMPLETED if payment was received and marked manually in the backend