Milwaukee police have arrested a 26-year-old man riding a bicycle for four sexual assaults which were reported last week.  Michael Raspberry is accused of grabbing the buttocks of one woman who was walking, then doing the same thing to a jogger one block away.  Police say he went on to grab a second walker two blocks farther along, then he allegedly chased a woman who was walking her dog, tackling her and ripping her pants as he pulled them down.  The suspect raced away when a car pulled into the parking lot, but he dropped his cell phone and a fingerprint matched Raspberry.  The attacks happened in an exclusive neighborhood on the city’s east side last week.