should provide a subcommand for showing pubkeys or privkeys given an account+passphrase like cli_wallet does

[sneak]

i attempted to newaccount and it added the keys to the local keyring using the new account's provided passphrase... but then failed when creating the account, leaving the keys in the wallet but no account created on the blockchain.

now, i've fixed that failure (now specifying the fee as a string and not an int) but the keys are already imported into the keyring (i don't know which, so i can't remove them) so it won't actually do the create now, it fails when attempting to re-import the passphrase-derived keys for the new account (which doesn't exist on the blockchain yet).

this would also be fixed by fixing #56 but such a helper command would be useful regardless. perhaps tying into importwif, but emulating the cli_wallet command get_private_key_from_password:

           pair<public_key_type, string> get_private_key_from_password(string account, string role, st
ring password)