hide secondary_database option behind "advanced" setup flag

src/database.js

@@ -1,14 +1,35 @@
-
+"use strict";
 
 var nconf = require('nconf'),
-	databaseType = nconf.get('database'),
-	winston = require('winston');
+	primaryDBConfig = nconf.get('database'),
+	secondaryDBConfig = nconf.get('secondary_database'),
+	secondaryModules = nconf.get('secondary_db_modules'),
+	winston = require('winston'),
 
-if(!databaseType) {
+	ALLOWED_MODULES = ['hash', 'list', 'sets', 'sorted'];
+
+if(!primaryDBConfig) {
 	winston.info('Database type not set! Run node app --setup');
 	process.exit();
 }
 
-var db = require('./database/' + databaseType);
+function setupSecondaryDB() {
+	var secondaryDB = require('./database/' + secondaryDBConfig);
 
-module.exports = db;
+	secondaryModules = secondaryModules.split(/,\s*/);
+
+	for (var module in secondaryModules) {
+		if (secondaryModules.hasOwnProperty(module) && ALLOWED_MODULES.indexOf(module) !== -1) {
+			primaryDB[module] = secondaryDB[module];
+		}
+	}
+}
+
+
+var primaryDB = require('./database/' + primaryDBConfig);
+
+if (secondaryDBConfig && secondaryModules) {
+	setupSecondaryDB();
+}
+
+module.exports = primaryDB;