This is a partial reversion of the earlier commit. Marking the password
option as required at the parser level made it impossible to run
./bisq-cli without options or arguments and get the help text. This is a
useful thing to do, and not worth creating a bad user experience to get
the free required option error handling and error messaging.
Don't instruct the user to create a fresh data directory every time, as
this takes quite a bit longer to initialize the wallet than running
against the same data directory repeatedly. Just be clear that the
requirement is an unencrypted wallet with 0 BTC balance.
