Add env variable PUPPETEER_OPEN_CHROME to decide whether to open chrome in test or not

jest-puppeteer.config.js

@@ -2,16 +2,17 @@
 require('dotenv').config()
 
 const port = process.env.PUPPETEER_PORT
+const host = process.env.PUPPETEER_HOST
+const openChrome = process.env.PUPPETEER_OPEN_CHROME
 
 module.exports = {
   server: {
-    command: `http-server --port ${port} ./www`,
+    command: `http-server -a 127.0.0.1 --port ${port} ./www`,
     port: port,
     launchTimeout: 5000
   },
-  
   launch: {
     dumpio: true,
-    headless: false,
+    headless: openChrome != 'true',
   },
 }