BOSTON — The first trial in the college admissions bribery scandal opened with defense attorneys seeking to portray the two parents accused of buying their kids’ way into school as victims of a con man who believed their payments were legitimate donations.Defense attorneys said former casino executive Gamal Abdelaziz and former Staples and Gap Inc. executive John Wilson never discussed paying bribes. They were assured by the admissions consultant at the center of the scheme that what they were doing was a …