NCBC-563: Inverted the assignment of ISaslMechanism and IOstrategy to avoid NRE

Change-Id: I86cf5e073aa0fee1f5a897d9498a18f49ff754de
Reviewed-on: http://review.couchbase.org/39890
Tested-by: Jeffry Morris <jeffrymorris@gmail.com>
Reviewed-by: Brett Lawson <brett19@gmail.com>