Merge pull request #70 from BastiaanLouis/support-2.1

Thanks @BastiaanLouis!

Helpers/ConversionHelper.cs

@@ -123,7 +123,7 @@ public static object MapStringTypeToCLRType(string type, object value)
                 case "Decimal":
                     return Convert.ChangeType(value, typeof(decimal));
                 case "Guid":
-                    return new Guid(value as string);
+                    return new Guid(value.ToString());
             }
             throw new NotSupportedException(string.Format(TypeNotSupported, type));
         }