Add fallback_locale to config

This is implemented in https://github.com/laravel/framework/commit/bf062fee1e0b67b2d646f37a7ef734ea5391c34c

app/config/app.php

@@ -54,6 +54,19 @@ return array(
 
 	'locale' => 'en',
 
+	/*
+	|--------------------------------------------------------------------------
+	| Application Fallback Locale
+	|--------------------------------------------------------------------------
+	|
+	| The fallback locale determines the locale to use when the current one
+	| is not available. You may change the value to correspond to any of
+	| the language folders that are provided through your application.
+	|
+	*/
+
+	'fallback_locale' => 'en',
+
 	/*
 	|--------------------------------------------------------------------------
 	| Encryption Key