[FEATURE] Add register user, issue currency to gateway api.
[FEATURE] Refactor cli registerUser function to cli module.
[FEATURE] Refactor list_users to cli module.
[CHORE] Add fund_hot_wallet ripple absraction.
[CHORE] clean up bin/config.
[FEATURE] Add ripple_abstract layer for ripple-only functions.
[FEATURE] Refactor bin/gateway fund_hot_walelt.