[TASK] rename paymentIsValid to isPaymentValid
[TASK] refactor fixtures
[TASK] add validated query parameter to submit payment route
[DOC] update API documentation for getAccountPayments
[TEST] reset earlier transactions test change
[TASK] refactor api structure to avoid using singletons
[TASK] refactor code to use app.respond instead of requiring respond for themselves
[TASK] refactor remote to be accessed through app's instance instead of being a singleton
[TASK] refactor db-interface to be accessed through app's instance
[TASK] remove unused remote
[DOC] add comments to info API endpoints
[DOC] add comments to balances API endpoint
[DOC] remove remote and dbinterface from comments