Began work on separating the unit tests from the integration tests. Moved TestingTool.cs to main project.
Started moving tests from the old test project to the new one. Also added a test for GetPaymentPlanParams.
Broke up InvoicePaymentTest in to two pieces. One for PrepareRequest and one for DoRequest.
Uncovered tests for a method (PaymentPlanPricePerMonth) that hadn't been implemented. Implemented said functionality and added test.
Added some additional integration tests from the Java package.
Merge branch 'feature/separate-test-suites' into develop