Query user for initial deposit amount

[holisticode]

Currently the DefaultInitialDepositAmount is a constant set to 0 (zero).

This makes it actually impossible for a user to cash in a cheque.
It is especially important for the devcon workshop that people can cash-in cheques.

We thus introduce an interactive prompt where the user can provide an initial deposit amount for the chequebook, which will be deducted from the user's account.

We also need to add a flag in order for tests and automated boots (cluster deployments) to run through and for convenience (user can pass value via flag instead of prompt).

Finally, we need to make sure that prompting is only done on first deployment. Once the chequebook is deployed, the user should not be prompted again.

Tackled by #1789 and #1797