- add requestId and slotIndex to Reservation (hopefully these will prove to be useful when we persist Reservations until request are completed, to add back bytes to Availability)
- add querying of all reservations, with accompanying tests
- change from find to findAvailabilities
- move onCleanUp from SalesContext to SalesAgent as it was getting overwritten for each slot processed
- remove sales agent AFTER deleting reservation, as this was causing some SIGSEGVs
- retrofit testsales and testslotqueue to match updated Reservations module API
* Simplify `.then` (promise api) and tests
* Remove tracked future when cancelled. Add tracked future tests
* Track and cancel statemachine futures
The futures created in each asyncstatemachine instance are tracked, and each future is cancelled and waited in `stop`.
Change `asyncstatemachine.stop` to be async so `machine.trackedFutures.cancelAndWait` could be called.
Add a constructor for `asyncstatemachine` that initialises the `trackedFutures` instance, and call the constructor from derived class constructors.
