Refactor configuration

- No longer use config npm package
- Prefer config from env vars, though still has support for config file
- No longer writes a config file for database config
- Writes keys to a new file in /data folder
- Removes a lot of cruft and improves config understanding

backend/models/now_helper.js

@@ -1,11 +1,11 @@
 const db     = require('../db');
-const config = require('config');
+const config = require('../lib/config');
 const Model  = require('objection').Model;
 
 Model.knex(db);
 
 module.exports = function () {
-	if (config.database.knex && config.database.knex.client === 'sqlite3') {
+	if (config.isSqlite()) {
 		// eslint-disable-next-line
 		return Model.raw("datetime('now','localtime')");
 	}