[TASK] Add balance_change array to transaction response, computed from metadata

Historically we've used semicolons to terminate lines and after functions. You don't *need* to use semicolons in JS anywhere, but we have, and for the sake of consistency we should keep it this way. Our code should look like it was written by one person. Forgetting or intentionally omitting semicolons in ripple-lib isn't excusable. Our style guide only says "Yup" https://github.com/ripple/javascript-style-guide#semicolons, could use more definition.