Allow boot/local.js file

It seems there's something incomplete about #15 as there's no way local.js is being included.

This should fix it.

@@ -11,17 +11,28 @@ exports = module.exports = function(config, local) {
 
   var env = process.env.NODE_ENV || 'development'
 
-  if (!_.isObject(config[env]))
-    throw new Error(util.format('Unknown environment %s', env))
-
   if (!_.isObject(local))
     local = {}
 
-  mergeDefaults(settings, local, config[env], config.defaults)
+  mergeDefaults(config, local)
+
+  if (!_.isObject(config[env]))
+    throw new Error(util.format('Unknown environment %s', env))
+
+  mergeDefaults(settings, config[env], config.defaults)
 
   return settings
 
 }
 
 exports['@singleton'] = true
-exports['@require'] = [ 'config' ]
+exports['@require'] = ['config']
+
+var fs = require('fs')
+var path = require('path')
+var localPath = path.join(__dirname, '..', '..', '..', '..' ,'boot', 'local.js')
+
+// Include local.js if it exists at boot/local.js
+if (fs.existsSync(localPath)) {
+  exports['@require'].push('local')
+}