refactor(config.js): Extract config file

* Separate different config source to each files
* Freeze config object

lib/config/oldEnvironment.js

@@ -0,0 +1,8 @@
+'use strict'
+
+module.exports = {
+  debug: process.env.DEBUG,
+  dburl: process.env.DATABASE_URL,
+  urlpath: process.env.URL_PATH,
+  port: process.env.PORT
+}