An ordinance allowing up to four medical marijuana dispensaries in the county, including two in West Marin, secured unanimous approval from the Board of Supervisors on Tuesday. The businesses, which will be able to deliver their goods, must be located at least 800 feet away from schools, youth-oriented facilities, smoke shops and other dispensaries. They will be limited to commercially zoned properties, making just 50 parcels in urban Marin eligible and just 134 parcels in…