Enabling nuget package restore and removing referenced nupkg files from repo U4-997

Implement Serialization framework from v5 U4-968

src/Umbraco.Core/Serialization/SerializationExtensions.cs

@@ -0,0 +1,40 @@
+using System;
+using System.IO;
+using System.Text;
+
+namespace Umbraco.Core.Serialization
+{
+    public static class SerializationExtensions
+    {
+        public static T FromJson<T>(this AbstractSerializationService service, string json, string intent = null)
+        {
+            if (string.IsNullOrWhiteSpace(json)) return default(T);
+            return (T)service.FromJson(json, typeof(T), intent);
+        }
+
+        public static T FromJson<T>(this ISerializer serializer, string json, string intent = null)
+        {
+            if (string.IsNullOrWhiteSpace(json)) return default(T);
+            return (T)serializer.FromJson(json, typeof(T));
+        }
+
+        public static object FromJson(this ISerializer serializer, string json, Type outputType)
+        {
+            if (string.IsNullOrWhiteSpace(json)) return outputType.GetDefaultValue();
+            var stream = new MemoryStream(Encoding.UTF8.GetBytes(json));
+            return serializer.FromStream(stream, outputType);
+        }
+
+        public static object FromJson(this AbstractSerializationService service, string json, Type outputType, string intent = null)
+        {
+            if (string.IsNullOrWhiteSpace(json)) return outputType.GetDefaultValue();
+            var stream = new MemoryStream(Encoding.UTF8.GetBytes(json));
+            return service.FromStream(stream, outputType, intent);
+        }
+
+        public static string ToJson(this AbstractSerializationService service, object input, string intent = null)
+        {
+            return StreamResultExtensions.ToJsonString(service.ToStream(input, intent).ResultStream);
+        }
+    }
+}