Implement of SendPayment() on okpay mock
Merge pull request #68 from sortega/task/70_send_payment

Implement of SendPayment() on okpay mock
Implement transactionGet
Replace Payment with Transaction on the okpaymock

This class can contain OKPay-specific information while payment should
be payment processor agnostic.
Make Payment covariant
Check for payments completion
Use Transaction_Not_Found SOAP fault
Improving logging and test of HanshakeArbiterActor

This should provide us with more information to fix the heisenbug
HandshakeArbiterActor has from time to time.
Merge pull request #69 from sortega/task/71_get_payment

Implementation of TransactionGet() in Fake OKPay
Add a proper logging configuration for tests

Typical testing logging is now 2k lines (was 8k before this configuration)
Merge pull request #70 from sortega/task/logging

Add a proper logging configuration for tests
Improve companions of FiatCurrency and FiatAmount
Implement balance reading on back office

This way we can test for wallet balances on integration tests
Merge pull request #71 from sortega/task/74_back_office

Implement balance reading on the back office api