update couchbase-api.php

Source: https://github.com/couchbase/php-ext-couchbase/pull/6
Change-Id: I43ffe7be471de827e339ff1bb1abaa2a221f39eb
Reviewed-on: http://review.couchbase.org/25848
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>