Use configured version of bignumber in all packages

packages/web3-wrapper/src/index.ts

@@ -1,6 +1,5 @@
 import { TransactionReceipt, TxData } from '@0xproject/types';
-import { bigNumberConfigs, promisify } from '@0xproject/utils';
-import BigNumber from 'bignumber.js';
+import { BigNumber, promisify } from '@0xproject/utils';
 import * as _ from 'lodash';
 import * as Web3 from 'web3';
 
@@ -15,9 +14,6 @@ interface RawLogEntry {
     topics: string[];
 }
 
-// Customize our BigNumber instances
-bigNumberConfigs.configure();
-
 export class Web3Wrapper {
     private _web3: Web3;
     private _defaults: Partial<TxData>;