Work around for non-serializable items

Depending on the products installed, some of the object members on the wrapper dicitonary may be non-serializable, breaking the export. (In the case I was working, this was caused by  an indexer product).

These changes discard the unserializable items if there are any. I may understand if it is desirable for an optional error-raising behavior instead - but let me know. (Note that the current behavior would not raise an error, just return an error string as the http content for the object)