Closed Issue: serialize null collection value [1605]

Currently, in webapi.odata v3 and later, it throws: "The 'ObjectContent`1' type failed to serialize the response body for content type

```
POST /odata/Products HTTP/1.1
{
"ID":1,
"Name":"abc"
}

HTTP/1.1 500 Internal Server Error
Cache-Control: private
Content-Type: application/json; charset=utf-8
Server: Microsoft-IIS/8.0
DataServiceVersion: 3.0
Date: Tue, 07 Jan 2014 15:10:46 GMT
Content-Length: 2727

{
"odata.error":{
"code":"","message":{
"lang":"en-US","value":"An error has occurred."
},"innererror":{
"message":"The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; charset=utf-8'.","type":"System.InvalidOperationException","stacktrace":"","internalexception":{
"message":"The argument must be of type 'IEnumerable'.\r\nParameter name: graph","type":"System.ArgumentException","stacktrace":" at System.Web.Http.OData.Formatter.Serialization.ODataCollectionSerializer.CreateODataValue(Object graph, IEdmTypeReference expectedType, ODataSerializerContext writeContext)\r\n at System.Web.Http.OData.Formatter.Serialization.ODataEdmTypeSerializer.CreateProperty(Object graph, IEdmTypeReference expectedType, String elementName, ODataSerializerContext writeContext)\r\n at System.Web.Http.OData.Formatter.Serialization.ODataEntityTypeSerializer.CreateStructuralProperty(IEdmStructuralProperty structuralProperty, EntityInstanceContext entityInstanceContext)\r\n at System.Web.Http.OData.Formatter.Serialization.ODataEntityTypeSerializer.CreateStructuralPropertyBag(IEnumerable`1 structuralProperties, EntityInstanceContext entityInstanceContext)\r\n at System.Web.Http.OData.Formatter.Serialization.ODataEntityTypeSerializer.CreateEntry(SelectExpandNode selectExpandNode, EntityInstanceContext entityInstanceContext)\r\n at System.Web.Http.OData.Formatter.Serialization.ODataEntityTypeSerializer.WriteEntry(Object graph, ODataWriter writer, ODataSerializerContext writeContext)\r\n at System.Web.Http.OData.Formatter.Serialization.ODataEntityTypeSerializer.WriteObjectInline(Object graph, IEdmTypeReference expectedType, ODataWriter writer, ODataSerializerContext writeContext)\r\n at System.Web.Http.OData.Formatter.Serialization.ODataEntityTypeSerializer.WriteObject(Object graph, Type type, ODataMessageWriter messageWriter, ODataSerializerContext writeContext)\r\n at System.Web.Http.OData.Formatter.ODataMediaTypeFormatter.WriteToStream(Type type, Object value, Stream writeStream, HttpContent content, HttpContentHeaders contentHeaders)\r\n at System.Web.Http.OData.Formatter.ODataMediaTypeFormatter.WriteToStreamAsync(Type type, Object value, Stream writeStream, HttpContent content, TransportContext transportContext)\r\n--- End of stack trace from previous location where exception was thrown ---\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at System.Web.Http.WebHost.HttpControllerHandler.<WriteBufferedResponseContentAsync>d__14.MoveNext()"
}
}
}
}
```

Sample model:
```
[DataContract]
public class Product
{
[DataMember]
public int ID { get; set; }

[DataMember]
public string Name { get; set; }

[DataMember(IsRequired=false)]
public string[] Aliases { get; set; }
}
```