Remove payout rule from project.

This reverts commit 37b05cb5952e5c083918f6eda74ed35f8c495695 - except for
the migration.
Remove payout_rule from projects.
Default payout_rule to 5% if not set.
Fix dependency issue in projects migration.
Make amounts editable for now.
Merge pull request #1011 from dokterbob/fees2

fees2: fixes for migrations.