Changing default of glueoutputbuf to UNSET since it has been removed fro...

...m redis since 2.6.

See Redis Release notes from 2.6: https://raw.github.com/antirez/redis/2.6/00-RELEASENOTES

Ultimately, this option should be removed eventually from this module - but for now to make this module backwards compatible - we should at least change this option to 'UNSET'.