JS: Add a way to convert an amount to a number.
JS: Add a way to convert an amount to a number.

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