Django-oscar-cybersource

- Make it possible to use a placeholder (``{order_number}``) in ``settings.CARD_REJECT_ERROR``.

- Add better error handling to the Cybersource response view. Prevents exceptions when a customer refreshes and resends one of the payment POST requests.

- Adds an order's shipping method into calls to Cybersource. This field can then be used by decision manager to help make decision regarding order fraud.
- Cybersource expects to receive one of the following values:
- `sameday`: courier or same-day service
- `oneday`: next day or overnight service
- `twoday`: two-day service
- `threeday`: three-day service
- `lowcost`: lowest-cost service
- `pickup`: store pick-up
- `other`: other shipping method
- `none`: no shipping method
- You can configure the mapping of Oscar shipping method code to Cybersource shipping method codes using the ``CYBERSOURCE_SHIPPING_METHOD_DEFAULT`` and ``CYBERSOURCE_SHIPPING_METHOD_MAPPING`` Django settings.
- Added exception handling and logging for bug sometimes occurring in the Cybersource reply handler.

- Add support for Django 1.11 and Oscar 1.5

- Improve testing with tox.

- Upgrade dependencies.