Use USPS_USER_ID env var in tests for user id

Author: benogle

test/city-test.js

@@ -3,7 +3,7 @@ const { test } = require('ava');
 
 const usps = new USPS({
   server: 'http://production.shippingapis.com/ShippingAPI.dll',
-  userId: '##'
+  userId: process.env.USPS_USER_ID
 });
 
 test.cb('#cityStateLookup() should return the city when passed a zipcode', t => {

test/validator-test.js

@@ -3,7 +3,7 @@ const { test } = require('ava');
 
 const usps = new USPS({
   server: 'http://production.shippingapis.com/ShippingAPI.dll',
-  userId: '##'
+  userId: process.env.USPS_USER_ID
 });
 
 test.cb('Address verify should validate apartment', t => {

test/zipcode-test.js

@@ -3,7 +3,7 @@ const { test } = require('ava');
 
 const usps = new USPS({
   server: 'http://production.shippingapis.com/ShippingAPI.dll',
-  userId: '##'
+  userId: process.env.USPS_USER_ID
 });
 
 const ZIP = '94607-3785';