got basic relationships working

added support for embedded documents.

NzbDrone.Core/Datastore/Converters/EmbeddedDocumentConverter.cs

@@ -0,0 +1,48 @@
+using System;
+using Marr.Data.Converters;
+using Marr.Data.Mapping;
+using Newtonsoft.Json;
+
+namespace NzbDrone.Core.Datastore.Converters
+{
+    public class EmbeddedDocumentConverter : IConverter
+    {
+        public object FromDB(ColumnMap map, object dbValue)
+        {
+            if (dbValue == DBNull.Value)
+            {
+                return DBNull.Value;
+            }
+
+            var stringValue = (string)dbValue;
+
+            if (string.IsNullOrWhiteSpace(stringValue))
+            {
+                return null;
+            }
+
+            return JsonConvert.DeserializeObject(stringValue, map.FieldType);
+        }
+
+        public object ToDB(object clrValue)
+        {
+            if (clrValue == null) return null;
+
+            if (clrValue as IEmbeddedDocument == null)
+            {
+                throw new InvalidOperationException("Attempted to embedded an object not marked with IEmbeddedDocument");
+            }
+
+            var json = JsonConvert.SerializeObject(clrValue);
+            return json;
+        }
+
+        public Type DbType
+        {
+            get
+            {
+                return typeof(string);
+            }
+        }
+    }
+}