update paypal express checkout documentation
Merge pull request #13 from joaoxsouls/master

update paypal express documentation
Upgrade dependencies
Add makefile for sandbox creation
Include default shipping charge in order total param

Previous version was failing to update the total amount when a list of
shipping methods was passed.

Fixes #14
Add coveralls support
Express success handler now creates an order payment event
Update sandbox to use more modern oscar templates
Include flake8
Sandbox checkout now creates payment sources as it should

Fixes #9
Update the Instant Update shipping callback handler

This commit cherry-picks the work of #16, where the API is updated to
reflect the latest PayPal docs:
https://developer.paypal.com/webapps/developer/docs/classic/api/merchant/Callback_API_Operation_NVP/

Fixes #16, #15
Update contributing docs
Correct coveralls behaviour
Update tox file to work with multiple Oscar versions
Restrict versions 0.3.* to Oscar < 0.5

Oscar 0.5 changes the way discounts are handled, which breaks
compatibility with the PayPal Express gateway.  It's better to not try
and be compatiable with both versions of Oscar - v0.4 of
django-oscar-paypal will support Oscar >= 0.5.

Fixes #17
Bump to v0.3.3
Bump version to 0.4-dev
Use django-oscar-testsupport

The test factories have been removed from Oscar in 0.5.
Patch test config with new settings for Oscar 0.5
Update submission of discounts for PayPal Express

Oscar 0.5 changes the ways discounts are handled.
This was spotted in #17.