Change the revision of the couchbase-python-client in perfrunner

Change-Id: I913c10f2afbef1db75caebae50d416d73895b267
Reviewed-on: http://review.couchbase.org/43213
Reviewed-by: Michael Wiederhold <mike@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>