Reset Session Data during second conversation

[terrenjpeterson]

need to remove all details from the session after a new session begins else will get wierd summaries like the following.

Big Mac is 540 calories. Roast Beef Salad is 140 calories and the Greek Dressing adds 230 calories. 12 oz. Coke is 150 calories. Total Calories are 140.

(the big mac and coke were left over from the prior session)