change BilingInvoice mapping to BIllingRequest
Removed the trigger event once the invoice has been paid, since product has already been activated by then
Added tests for BillingInvoiceManager
Update BillingInvoiceMgr to match changes in BillingInvoice to BillingRequest
Fixed unit test bootstrap
Refactoring BillingInvoiceManager to use BillingRequest
Merge pull request #6 from immersivelabs/feature/invoice

[RFC] Invoice Integration