Refactoring

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

It's Yavsc, not one of its lib.

src/Api/Controllers/PostRateApiController.cs

@@ -4,6 +4,7 @@ using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Mvc;
 using Yavsc.Helpers;
 using Yavsc.Models;
+using Yavsc.Server.Helpers;
 
 namespace Yavsc.Controllers
 {