Split tokens package into erc20 and erc721

contracts/extensions/test/utils/balance_threshold_wrapper.ts

@@ -1,3 +1,5 @@
+import { artifacts as erc20Artifacts } from '@0x/contracts-erc20';
+import { artifacts as erc721Artifacts } from '@0x/contracts-erc721';
 import { artifacts as exchangeArtifacts, ExchangeContract } from '@0x/contracts-exchange';
 import {
     FillResults,
@@ -7,7 +9,6 @@ import {
     orderUtils,
     TransactionFactory,
 } from '@0x/contracts-test-utils';
-import { artifacts as tokensArtifacts } from '@0x/contracts-tokens';
 import { SignedOrder } from '@0x/types';
 import { BigNumber } from '@0x/utils';
 import { Web3Wrapper } from '@0x/web3-wrapper';
@@ -35,7 +36,8 @@ export class BalanceThresholdWrapper {
         this._web3Wrapper = new Web3Wrapper(provider);
         this._logDecoder = new LogDecoder(this._web3Wrapper, {
             ...artifacts,
-            ...tokensArtifacts,
+            ...erc20Artifacts,
+            ...erc721Artifacts,
             ...exchangeArtifacts,
         });
     }