Feature/payouts

This adds ProjectPayouts.
Payouts are mostly a copy and paste job from what was in 1%. Simplified and adapted coding style to make it fitter better with the other Bluebottle apps.
Also see https://www.lucidchart.com/documents/edit/bd196f9e-0f9f-4f32-8cd0-94dd4fec5688

- Add bb_payouts and payouts apps.
- Add status Pending to orders.
- Use init_projects in most TestCases so all phases that payouts rely on are present.

Again Mathijs's code, but this is the way you can create methods that you can call e.g. in admin list_fields with some params. 
Same like https://github.com/onepercentclub/bluebottle/blob/master/bluebottle/utils/admin.py