Fixup all warnings from the mock.client package

Change-Id: Ie1c7723d0d085b7e6ae24840645ccbfdfcd13be8
Reviewed-on: http://review.couchbase.org/27924
Reviewed-by: Mark Nunberg <mnunberg@haskalah.org>
Tested-by: Trond Norbye <trond.norbye@gmail.com>