Fix login page url (#1278)

Use Flake framework to get login url.
Otherwise slashes in the end of the urls are not handled correctly.
Basically reverts 2ee4be6

Core/Frameworks/BaikalAdmin/Controller/Login.php

@@ -34,7 +34,7 @@ function execute() {
     }
 
     function render() {
-        $sActionUrl = PROJECT_BASEURI;
+        $sActionUrl = $GLOBALS["ROUTER"]::buildRoute("default", []);
         $sSubmittedFlagName = "auth";
         $sMessage = "";