Tests pass under Oscar 0.7.1

Will need to modify Oscar to allow basket to be passed through to
build_submission.
Drop support for Oscar 0.5
Pass empty string instead of None for address fields
Use i18n URLs in sandbox

Fixes #70
Improve express dashboard templates
Remove HTML from templates required for Oscar 0.5
Clean up the success response view

- Add logging
- Pass variables around more explicitly
- Remove fetch_paypal_data method
Upgrade deps to latest

And include detox