* Added machine model, and new database relations

* Added first centralized database config and  added machine self-registration into db
* Fix database migration with new database
* Refactor

Step.Database/Controllers/MachinesUsersController.cs

@@ -0,0 +1,36 @@
+using Step.Model.DatabaseModels;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Step.Database.Controllers
+{
+    public class MachinesUsersController : IDisposable
+    {
+        private DatabaseContext dbCtx;
+
+        public MachinesUsersController()
+        {
+            // Initialize database context
+            dbCtx = new DatabaseContext();
+        }
+
+        public void Dispose()
+        {
+            // Clear database context
+            dbCtx.Dispose();
+        }
+        
+        public MachinesUsersModel FindByUserId(int machineId, int userId)
+        {
+            return dbCtx
+                .MachinesUsers
+                .Include("Role")
+                .Where(x => x.MachineId == machineId && x.UserId == userId)
+                .FirstOrDefault();
+ 
+        }
+    }
+}