Improve documentation. Update dependencies.

Author: daquinoaldo

README.md

@@ -13,6 +13,22 @@ It works with MacOS, Linux and Windows, on Chrome and Firefox, and requires you
 [![GitHub issues](https://img.shields.io/github/issues/daquinoaldo/https-localhost.svg)](https://github.com/daquinoaldo/https-localhost/issues)
 
 
+## Dependencies
+nss/certutils are needed for Firefox and Chrome.
+#### MacOS
+```
+brew install nss
+```
+#### Linux
+```
+sudo apt install libnss3-tools
+    -or-
+sudo yum install nss-tools
+    -or-
+sudo pacman -S nss
+```
+
+
 ## Install and use standalone
 ```
 npm i -g --only=prod https-localhost

index.js

@@ -40,8 +40,8 @@ const createServer = () => {
     /* istanbul ignore next: cannot be tested on Travis */ httpPort = 80,
     httpsPort = process.env.PORT || 443) {
     app.http = http.createServer((req, res) => {
-      const reqHost = req.headers["host"]
-        ? req.headers["host"].replace(":" + httpPort, "")
+      const reqHost = req.headers.host
+        ? req.headers.host.replace(":" + httpPort, "")
         : /* istanbul ignore next: cannot be tested */ "localhost"
       res.writeHead(301, {
         Location: "https://" + reqHost +