Try to load `payload_object` created with `YAML::syck` parser

This pull-request aims to fix a rare case when handler contains YAML-encoded data that was serialized with  `syck` YAML parser. delayed_job crashes when worker tries to deserialize this data.

Although this issue might be very specific and subjective to our application I still would like to submit this fix. Let me know if this can be merged and/or I should add some tests for this case.

Thanks,
Igor