Add computeLedgerHash method

src/api/index.js

@@ -30,6 +30,7 @@ const errors = require('./common').errors;
 const convertExceptions = require('./common').convertExceptions;
 const generateWallet = convertExceptions(common.core.Wallet.generate);
 const getLedgerHeader = require('./ledger/ledger-header');
+const computeLedgerHash = require('./offline/ledgerhash');
 
 function RippleAPI(options: {}) {
   const _options = _.assign({}, options, {automatic_resubmission: false});
@@ -63,6 +64,7 @@ RippleAPI.prototype = {
   sign,
   submit,
 
+  computeLedgerHash,
   generateWallet,
   errors
 };