Add state pending_ext
TransactionService
Fix tests, remove old code
Return updated transaction entity
Improvements to the service
Rename datatype creation methods
Merge pull request #675 from sharetribe/pending_ext

Paypal: Pending
Add billing agreement created spec
Make receipt id optional
Add paypal refunds
Paypal refunding service and ipn handling
Limit string db fields
Add validations for paypal refund