added json.net tests for mono.

NzbDrone.Libraries.Test/Json/JsonFixture.cs

@@ -0,0 +1,24 @@
+using NUnit.Framework;
+using Newtonsoft.Json;
+
+namespace NzbDrone.Libraries.Test.Json
+{
+    [TestFixture]
+    public class JsonFixture
+    {
+        public class TypeWithNumbers
+        {
+            public int Id { get; set; }
+        }
+
+        [Test]
+        public void should_be_able_to_deserialize_numbers()
+        {
+            var quality = new TypeWithNumbers { Id = 12 };
+
+            var json = JsonConvert.SerializeObject(quality);
+
+            JsonConvert.DeserializeObject(json);
+        }
+    }
+}