Refactoring

The main server owns the migrations, it's the server part,
it's simpler.

It's Yavsc, not one of its lib.

src/Yavsc/Controllers/Administration/AdministrationController.cs

@@ -7,6 +7,7 @@ using Microsoft.EntityFrameworkCore;
 using Yavsc.Abstract.Identity;
 using Yavsc.Helpers;
 using Yavsc.Models;
+using Yavsc.Server.Helpers;
 using Yavsc.ViewModels;
 using Yavsc.ViewModels.Administration;