new IJsonSerializer, moves other base cache refresher classes

src/Umbraco.Core/Serialization/JsonNetSerializer.cs

@@ -0,0 +1,22 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Newtonsoft.Json;
+
+namespace Umbraco.Core.Serialization
+{
+    public class JsonNetSerializer : IJsonSerializer
+    {
+        public string Serialize(object input)
+        {
+            return JsonConvert.SerializeObject(input);
+        }
+
+        public T Deserialize<T>(string input)
+        {
+            return JsonConvert.DeserializeObject<T>(input);
+        }
+    }
+}