UT add testing for ledger_closed and update ledger_current.
UT add testing for ledger_closed and update ledger_current.

ripple/ripple-lib,darkdarkdragon/ripple-lib,ripple/ripple-lib,darkdarkdragon/ripple-lib,wilsonianb/ripple-lib,darkdarkdragon/ripple-lib,ripple/ripple-lib,wilsonianb/ripple-lib,wilsonianb/ripple-lib,ripple/ripple-lib