Improve the way superblock challengers and submitters deposit and withdraw eth

[oscarguindzberg]

Currently, they send a deposit before doing each action.
Create a mechanism where they can deposit and withdraw eth once a day or something like that.

[oscarguindzberg]

Current implementation:
before submitting a superblock, the submitter adds 1000 wei as deposit.
Currently, before doing a challenge, the submitter adds 1000 wei as deposit.
The challenger does not add deposit on a query. The defender does not add a deposit when anwsering a query. So far, it will no break the demo, since 1000 wei deposit is added on submit/challenge.
Design a better mechanism.
Option to consider: Should we write a DepositManagerClient that adds/removes deposit to keep a reasonable deposit at all times?