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.

Hmm, this is not a small change. Do we really want to include pending payments to calculate amounts donated?