Remove -M to disable eviction

This option is only valid for default_engine and should be
configured through eviction=false;

Change-Id: I24e00de878277a418748dd642fb81b62042d32cd
Reviewed-on: http://review.couchbase.org/33081
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>