move all models into core

src/Api/Models/Response/KeysResponseModel.cs

@@ -1,23 +0,0 @@
-using System;
-using Bit.Core.Models.Table;
-
-namespace Bit.Api.Models
-{
-    public class KeysResponseModel : ResponseModel
-    {
-        public KeysResponseModel(User user)
-            : base("keys")
-        {
-            if(user == null)
-            {
-                throw new ArgumentNullException(nameof(user));
-            }
-
-            PublicKey = user.PublicKey;
-            PrivateKey = user.PrivateKey;
-        }
-
-        public string PublicKey { get; set; }
-        public string PrivateKey { get; set; }
-    }
-}