Torts — Negligence — Security services — In action by plaintiff who was attacked and injured in parking garage owned by county at a time when no security guard was present against company which had contracted with county to provide security services at parking garage, trial court properly entered summary judgment for defendant security company on basis that under provisions of contract between security company and county, county retained control over shift schedule and number of guards assigned to garage — Defendant did not assume county’s duty to protect plaintiff where county had determined that garage was only to be staffed by a security guard from 7 a.m. to 7 p.m. and plaintiff was attacked after 7 p.m. in the evening