Fix TSLint issues

packages/contract-wrappers/test/global_hooks.ts

@@ -5,7 +5,7 @@ import * as path from 'path';
 import { constants } from './utils/constants';
 import { provider } from './utils/web3_wrapper';
 
-before('migrate contracts', async function() {
+before('migrate contracts', async function(): Promise<void> {
     // HACK: Since the migrations take longer then our global mocha timeout limit
     // we manually increase it for this before hook.
     this.timeout(20000);

packages/contract-wrappers/test/utils/chai_setup.ts

@@ -4,7 +4,7 @@ import ChaiBigNumber = require('chai-bignumber');
 import * as dirtyChai from 'dirty-chai';
 
 export const chaiSetup = {
-    configure() {
+    configure(): void {
         chai.config.includeStack = true;
         chai.use(ChaiBigNumber());
         chai.use(dirtyChai);