Support OpenSea bundles

[elsewhat]

Currently bundles has a different structure.
They are detected and skipped through:

                if not openseaEvent['asset'] and openseaEvent['asset_bundle']:
                    print("Bundles from OpenSea are currently not supported. Skipped bundle \"{}\"".format(openseaEvent['asset_bundle']['name'] ))
                    continue

Will need to split the cost for the whole transaction into the sellTransaction for each NFT