Add docker container definition

Change-Id: If32020e6b8e8bb816eb54533554b18cc5302b5c9
diff --git a/php/login.php b/php/login.php
index f86aa68..c06149e 100644
--- a/php/login.php
+++ b/php/login.php
@@ -4,7 +4,7 @@
 	require_once("security.php");
 
 	$credentials = new Credentials();
-	$usersdb = $credentials->usersdb;
+	$usersdb = $credentials->usersdb();
 
 	date_default_timezone_set("Europe/Madrid");