`submitAndWait` in standalone mode

[tequdev]

We cannot use submitAndWait in a standalone mode network.

I propose to add a standalone flag to the submitAndWait parameter so that the ledger_accept command can be executed in the process.

Ideally, it should be able to run in stand-alone mode and on other testnets with nearly identical simple code, although it is possible to do so in other ways.

[mvadari]

Is this necessary when you can just use submit and run ledger_accept yourself?