First step to removing OrderItem.
Second step to removing OrderItem.

Conflicts:
	apps/recurring_donations/management/commands/process_monthly_donations.py
Add 'manually_process' field to RecurringDirectDebitPayment.

This is needed for the monthly payments that can't be processed
automatically.
Rename recurring_donations app to donations.
Merge pull request #780 from benkonrath/order-orderitem-remove

Order orderitem remove