Use make-promises-safe to catch unhandled rejections in tests

packages/dev-utils/package.json

@@ -2,7 +2,7 @@
     "name": "@0xproject/dev-utils",
     "version": "0.4.1",
     "engines": {
-        "node" : ">=6.12"
+        "node": ">=6.12"
     },
     "description": "0x dev TS utils",
     "main": "lib/src/index.js",
@@ -35,6 +35,7 @@
         "@types/mocha": "^2.2.42",
         "chai": "^4.0.1",
         "copyfiles": "^1.2.0",
+        "make-promises-safe": "^1.1.0",
         "mocha": "^4.0.1",
         "npm-run-all": "^4.1.2",
         "nyc": "^11.0.1",

packages/dev-utils/test/blockchain_lifecycle_test.ts

@@ -1,6 +1,7 @@
 import { BlockParamLiteral } from '@0xproject/types';
 import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import * as chai from 'chai';
+import 'make-promises-safe';
 import 'mocha';
 
 import { BlockchainLifecycle, web3Factory } from '../src';

packages/dev-utils/test/rpc_test.ts

@@ -1,6 +1,7 @@
 import { BlockParamLiteral } from '@0xproject/types';
 import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import * as chai from 'chai';
+import 'make-promises-safe';
 import 'mocha';
 
 import { web3Factory } from '../src';